diff --git a/.gitignore b/.gitignore
index 4901aab..8ae88e5 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,3 +1,3 @@
 /vendor
 /composer.lock
-/.phpunit.result.cache
+/.phpunit.cache
diff --git a/composer.json b/composer.json
index 17b163c..95d67dd 100644
--- a/composer.json
+++ b/composer.json
@@ -17,7 +17,7 @@
         "php": "^8.1"
     },
     "require-dev": {
-        "phpunit/phpunit": "^9.0",
+        "phpunit/phpunit": "^10.0",
         "php-coveralls/php-coveralls": "^2.2",
         "vimeo/psalm": "5.14.1"
     },
diff --git a/phpunit.xml b/phpunit.xml
index a292a18..bfaec18 100644
--- a/phpunit.xml
+++ b/phpunit.xml
@@ -1,13 +1,13 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" colors="true" bootstrap="phpunit.php" xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/9.3/phpunit.xsd">
+<phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" colors="true" bootstrap="phpunit.php" xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/10.2/phpunit.xsd" cacheDirectory=".phpunit.cache">
     <testsuites>
         <testsuite name="Math tests">
             <directory>tests</directory>
         </testsuite>
     </testsuites>
-    <coverage processUncoveredFiles="true">
+    <source>
         <include>
-            <directory suffix=".php">src</directory>
+            <directory>src</directory>
         </include>
-    </coverage>
+    </source>
 </phpunit>
diff --git a/tests/BigDecimalTest.php b/tests/BigDecimalTest.php
index f8d3443..700d4c4 100644
--- a/tests/BigDecimalTest.php
+++ b/tests/BigDecimalTest.php
@@ -29,7 +29,7 @@ public function testOf($value, string $unscaledValue, int $scale) : void
         self::assertBigDecimalInternalValues($unscaledValue, $scale, BigDecimal::of($value));
     }
 
-    public function providerOf() : array
+    public static function providerOf() : array
     {
         return [
             [0, '0', 0],
@@ -206,7 +206,7 @@ public function testOfFloatInDifferentLocales(string $locale) : void
         setlocale(LC_NUMERIC, $originalLocale);
     }
 
-    public function providerOfFloatInDifferentLocales() : array
+    public static function providerOfFloatInDifferentLocales() : array
     {
         return [
             ['C'],
@@ -231,7 +231,7 @@ public function testOfInvalidValueThrowsException($value) : void
         BigDecimal::of($value);
     }
 
-    public function providerOfInvalidValueThrowsException() : array
+    public static function providerOfInvalidValueThrowsException() : array
     {
         return [
             [''],
@@ -282,7 +282,7 @@ public function testOfUnscaledValue($unscaledValue, int $scale, string $expected
         self::assertBigDecimalInternalValues($expectedUnscaledValue, $scale, $number);
     }
 
-    public function providerOfUnscaledValue() : array
+    public static function providerOfUnscaledValue() : array
     {
         return [
             [123456789, 0, '123456789'],
@@ -347,7 +347,7 @@ public function testMin(array $values, string $min) : void
         self::assertBigDecimalEquals($min, BigDecimal::min(... $values));
     }
 
-    public function providerMin() : array
+    public static function providerMin() : array
     {
         return [
             [[0, 1, -1], '-1'],
@@ -388,7 +388,7 @@ public function testMax(array $values, string $max) : void
         self::assertBigDecimalEquals($max, BigDecimal::max(... $values));
     }
 
-    public function providerMax() : array
+    public static function providerMax() : array
     {
         return [
             [[0, 0.9, -1.00], '0.9'],
@@ -433,7 +433,7 @@ public function testSum(array $values, string $sum) : void
         self::assertBigDecimalEquals($sum, BigDecimal::sum(... $values));
     }
 
-    public function providerSum() : array
+    public static function providerSum() : array
     {
         return [
             [[0, 0.9, -1.00], '-0.1'],
@@ -480,7 +480,7 @@ public function testPlus(string $a, string $b, string $unscaledValue, int $scale
         self::assertBigDecimalInternalValues($unscaledValue, $scale, BigDecimal::of($a)->plus($b));
     }
 
-    public function providerPlus() : array
+    public static function providerPlus() : array
     {
         return [
             ['123',    '999',    '1122',   0],
@@ -556,7 +556,7 @@ public function testMinus(string $a, string $b, string $unscaledValue, int $scal
         self::assertBigDecimalInternalValues($unscaledValue, $scale, BigDecimal::of($a)->minus($b));
     }
 
-    public function providerMinus() : array
+    public static function providerMinus() : array
     {
         return [
             ['123',    '999',    '-876',   0],
@@ -625,7 +625,7 @@ public function testMultipliedBy(string $a, string $b, string $unscaledValue, in
         self::assertBigDecimalInternalValues($unscaledValue, $scale, BigDecimal::of($a)->multipliedBy($b));
     }
 
-    public function providerMultipliedBy() : array
+    public static function providerMultipliedBy() : array
     {
         return [
             ['123',    '999',    '122877',     0],
@@ -739,7 +739,7 @@ public function testDividedBy(string $a, string $b, ?int $scale, int $roundingMo
         self::assertBigDecimalInternalValues($unscaledValue, $expectedScale, $decimal);
     }
 
-    public function providerDividedBy() : array
+    public static function providerDividedBy() : array
     {
         return [
             [ '7',  '0.2', 0, RoundingMode::UNNECESSARY,  '35', 0],
@@ -774,7 +774,7 @@ public function testDividedByByZeroThrowsException($zero) : void
         BigDecimal::of(1)->dividedBy($zero, 0);
     }
 
-    public function providerDividedByByZeroThrowsException() : array
+    public static function providerDividedByByZeroThrowsException() : array
     {
         return [
             [0],
@@ -807,7 +807,7 @@ public function testExactlyDividedBy($number, $divisor, string $expected) : void
         }
     }
 
-    public function providerExactlyDividedBy() : array
+    public static function providerExactlyDividedBy() : array
     {
         return [
             [1, 1, '1'],
@@ -860,7 +860,7 @@ public function testDividedByWithRoundingNecessaryThrowsException(string $a, str
         BigDecimal::of($a)->dividedBy($b, $scale);
     }
 
-    public function providerDividedByWithRoundingNecessaryThrowsException() : array
+    public static function providerDividedByWithRoundingNecessaryThrowsException() : array
     {
         return [
             ['1.234', '123.456', 3],
@@ -921,7 +921,7 @@ private function doTestRoundingMode(int $roundingMode, BigDecimal $number, strin
         }
     }
 
-    public function providerRoundingMode() : array
+    public static function providerRoundingMode() : array
     {
         return [
             [RoundingMode::UP,  '3.501',  '351',  '36',  '4'],
@@ -1407,7 +1407,7 @@ public function testQuotientAndRemainder(string $dividend, string $divisor, stri
         self::assertBigDecimalEquals($remainder, $r);
     }
 
-    public function providerQuotientAndRemainder() : array
+    public static function providerQuotientAndRemainder() : array
     {
         return [
             ['1', '123', '0', '1'],
@@ -1504,7 +1504,7 @@ public function testSqrt(string $number, int $scale, string $sqrt) : void
         self::assertBigDecimalEquals($sqrt, $number->sqrt($scale));
     }
 
-    public function providerSqrt() : array
+    public static function providerSqrt() : array
     {
         return [
             ['0', 0, '0'],
@@ -1728,7 +1728,7 @@ public function testPower(string $number, int $exponent, string $unscaledValue,
         self::assertBigDecimalInternalValues($unscaledValue, $scale, BigDecimal::of($number)->power($exponent));
     }
 
-    public function providerPower() : array
+    public static function providerPower() : array
     {
         return [
             ['-3', 0, '1', 0],
@@ -1788,7 +1788,7 @@ public function testPowerWithInvalidExponentThrowsException(int $power) : void
         BigDecimal::of(1)->power($power);
     }
 
-    public function providerPowerWithInvalidExponentThrowsException() : array
+    public static function providerPowerWithInvalidExponentThrowsException() : array
     {
         return [
             [-1],
@@ -1797,7 +1797,7 @@ public function providerPowerWithInvalidExponentThrowsException() : array
     }
 
     /**
-     * @dataProvider toScaleProvider
+     * @dataProvider providerToScale
      *
      * @param string $number        The number to scale.
      * @param int    $toScale       The scale to apply.
@@ -1811,7 +1811,7 @@ public function testToScale(string $number, int $toScale, int $roundingMode, str
         self::assertBigDecimalInternalValues($unscaledValue, $scale, $decimal);
     }
 
-    public function toScaleProvider() : array
+    public static function providerToScale() : array
     {
         return [
             ['123.45', 0, RoundingMode::DOWN, '123', 0],
@@ -1833,7 +1833,7 @@ public function testWithPointMovedLeft(string $number, int $places, string $expe
         self::assertBigDecimalEquals($expected, BigDecimal::of($number)->withPointMovedLeft($places));
     }
 
-    public function providerWithPointMovedLeft() : array
+    public static function providerWithPointMovedLeft() : array
     {
         return [
             ['0', -2, '0'],
@@ -1916,7 +1916,7 @@ public function testWithPointMovedRight(string $number, int $places, string $exp
         self::assertBigDecimalEquals($expected, BigDecimal::of($number)->withPointMovedRight($places));
     }
 
-    public function providerWithPointMovedRight() : array
+    public static function providerWithPointMovedRight() : array
     {
         return [
             ['0', -2, '0.00'],
@@ -1998,7 +1998,7 @@ public function testStripTrailingZeros(string $number, string $expected) : void
         self::assertBigDecimalEquals($expected, BigDecimal::of($number)->stripTrailingZeros());
     }
 
-    public function providerStripTrailingZeros() : array
+    public static function providerStripTrailingZeros() : array
     {
         return [
             ['0', '0'],
@@ -2044,7 +2044,7 @@ public function testAbs(string $number, string $unscaledValue, int $scale) : voi
         self::assertBigDecimalInternalValues($unscaledValue, $scale, BigDecimal::of($number)->abs());
     }
 
-    public function providerAbs() : array
+    public static function providerAbs() : array
     {
         return [
             ['123', '123', 0],
@@ -2066,7 +2066,7 @@ public function testNegated(string $number, string $unscaledValue, int $scale) :
         self::assertBigDecimalInternalValues($unscaledValue, $scale, BigDecimal::of($number)->negated());
     }
 
-    public function providerNegated() : array
+    public static function providerNegated() : array
     {
         return [
             ['123', '-123', 0],
@@ -2148,7 +2148,7 @@ public function testIsGreaterThanOrEqualTo(string $a, $b, int $c) : void
         self::assertSame($c >= 0, BigDecimal::of($a)->isGreaterThanOrEqualTo($b));
     }
 
-    public function providerCompareTo() : array
+    public static function providerCompareTo() : array
     {
         return [
             ['123', '123',  0],
@@ -2263,7 +2263,7 @@ public function testIsPositiveOrZero($number, int $sign) : void
         self::assertSame($sign >= 0, BigDecimal::of($number)->isPositiveOrZero());
     }
 
-    public function providerSign() : array
+    public static function providerSign() : array
     {
         return [
             [ 0,  0],
@@ -2307,7 +2307,7 @@ public function testGetIntegralPart(string $number, string $expected) : void
         self::assertSame($expected, BigDecimal::of($number)->getIntegralPart());
     }
 
-    public function providerGetIntegralPart() : array
+    public static function providerGetIntegralPart() : array
     {
         return [
             ['1.23', '1'],
@@ -2331,7 +2331,7 @@ public function testGetFractionalPart(string $number, string $expected) : void
         self::assertSame($expected, BigDecimal::of($number)->getFractionalPart());
     }
 
-    public function providerGetFractionalPart() : array
+    public static function providerGetFractionalPart() : array
     {
         return [
             ['1.23', '23'],
@@ -2354,7 +2354,7 @@ public function testHasNonZeroFractionalPart(string $number, bool $hasNonZeroFra
         self::assertSame($hasNonZeroFractionalPart, BigDecimal::of($number)->hasNonZeroFractionalPart());
     }
 
-    public function providerHasNonZeroFractionalPart() : array
+    public static function providerHasNonZeroFractionalPart() : array
     {
         return [
             ['1', false],
@@ -2377,7 +2377,7 @@ public function testToBigInteger(string $decimal, string $expected) : void
         self::assertBigIntegerEquals($expected, BigDecimal::of($decimal)->toBigInteger());
     }
 
-    public function providerToBigInteger() : array
+    public static function providerToBigInteger() : array
     {
         return [
             ['0', '0'],
@@ -2399,7 +2399,7 @@ public function testToBigIntegerThrowsExceptionWhenRoundingNecessary(string $dec
         BigDecimal::of($decimal)->toBigInteger();
     }
 
-    public function providerToBigIntegerThrowsExceptionWhenRoundingNecessary() : array
+    public static function providerToBigIntegerThrowsExceptionWhenRoundingNecessary() : array
     {
         return [
             ['0.1'],
@@ -2425,7 +2425,7 @@ public function testToBigRational(string $decimal, string $rational) : void
         self::assertBigRationalEquals($rational, BigDecimal::of($decimal)->toBigRational());
     }
 
-    public function providerToBigRational() : array
+    public static function providerToBigRational() : array
     {
         return [
             ['0', '0'],
@@ -2469,7 +2469,7 @@ public function testToInt(int $number) : void
         self::assertSame($number, BigDecimal::of($number . '.0')->toInt());
     }
 
-    public function providerToInt() : array
+    public static function providerToInt() : array
     {
         return [
             [PHP_INT_MIN],
@@ -2493,7 +2493,7 @@ public function testToIntThrowsException(string $number) : void
         BigDecimal::of($number)->toInt();
     }
 
-    public function providerToIntThrowsException() : array
+    public static function providerToIntThrowsException() : array
     {
         return [
             ['-999999999999999999999999999999'],
@@ -2514,7 +2514,7 @@ public function testToFloat(string $value, float $float) : void
         self::assertSame($float, BigDecimal::of($value)->toFloat());
     }
 
-    public function providerToFloat() : array
+    public static function providerToFloat() : array
     {
         return [
             ['0', 0.0],
@@ -2539,7 +2539,7 @@ public function testToString(string $unscaledValue, int $scale, string $expected
         self::assertSame($expected, (string) BigDecimal::ofUnscaledValue($unscaledValue, $scale));
     }
 
-    public function providerToString() : array
+    public static function providerToString() : array
     {
         return [
             ['0',   0, '0'],
diff --git a/tests/BigIntegerTest.php b/tests/BigIntegerTest.php
index 2c4aa89..54e9301 100644
--- a/tests/BigIntegerTest.php
+++ b/tests/BigIntegerTest.php
@@ -32,7 +32,7 @@ public function testOf($value, string $expected) : void
         self::assertBigIntegerEquals($expected, BigInteger::of($value));
     }
 
-    public function providerOf() : array
+    public static function providerOf() : array
     {
         return [
             [0, '0'],
@@ -122,7 +122,7 @@ public function testOfInvalidFormatThrowsException($value) : void
         BigInteger::of($value);
     }
 
-    public function providerOfInvalidFormatThrowsException() : array
+    public static function providerOfInvalidFormatThrowsException() : array
     {
         return [
             [''],
@@ -151,7 +151,7 @@ public function testOfNonConvertibleValueThrowsException($value) : void
         BigInteger::of($value);
     }
 
-    public function providerOfNonConvertibleValueThrowsException() : array
+    public static function providerOfNonConvertibleValueThrowsException() : array
     {
         return [
             [1.1],
@@ -175,7 +175,7 @@ public function testFromBase(string $number, int $base, string $expected) : void
     /**
      * @return array
      */
-    public function providerFromBase() : array
+    public static function providerFromBase() : array
     {
         return [
             ['0', 10, '0'],
@@ -289,7 +289,7 @@ public function testFromBaseWithInvalidValue(string $value, int $base) : void
         BigInteger::fromBase($value, $base);
     }
 
-    public function providerFromBaseWithInvalidValue() : array
+    public static function providerFromBaseWithInvalidValue() : array
     {
         return [
             ['', 10],
@@ -345,7 +345,7 @@ public function testFromBaseWithInvalidBase(int $base) : void
         BigInteger::fromBase('0', $base);
     }
 
-    public function providerFromBaseWithInvalidBase() : array
+    public static function providerFromBaseWithInvalidBase() : array
     {
         return [
             [-2],
@@ -387,7 +387,7 @@ public function testGcdMultiple(array $values, string $expectedGCD): void
         self::assertSame($expectedGCD, (string) $actualGCD);
     }
 
-    public function providerGcdMultiple(): Generator
+    public static function providerGcdMultiple(): Generator
     {
         // 1 value
         foreach (['-2', '-1', '0', '1', '2'] as $value) {
@@ -395,7 +395,7 @@ public function providerGcdMultiple(): Generator
         }
 
         // 2 values
-        foreach ($this->providerGcd() as [$a, $b, $gcd]) {
+        foreach (self::providerGcd() as [$a, $b, $gcd]) {
             yield [[$a, $b], $gcd];
         }
 
@@ -425,7 +425,7 @@ public function testMin(array $values, string $min) : void
         self::assertBigIntegerEquals($min, BigInteger::min(... $values));
     }
 
-    public function providerMin() : array
+    public static function providerMin() : array
     {
         return [
             [[0, 1, -1], '-1'],
@@ -461,7 +461,7 @@ public function testMax(array $values, string $max) : void
         self::assertBigIntegerEquals($max, BigInteger::max(... $values));
     }
 
-    public function providerMax() : array
+    public static function providerMax() : array
     {
         return [
             [[0, 1, -1], '1'],
@@ -498,7 +498,7 @@ public function testSum(array $values, string $sum) : void
         self::assertBigIntegerEquals($sum, BigInteger::sum(... $values));
     }
 
-    public function providerSum() : array
+    public static function providerSum() : array
     {
         return [
             [[-1], '-1'],
@@ -537,7 +537,7 @@ public function testPlus(string $a, string $b, string $r) : void
         self::assertBigIntegerEquals($r, BigInteger::of($a)->plus($b));
     }
 
-    public function providerPlus() : array
+    public static function providerPlus() : array
     {
         return [
             ['5165450198704521651351654564564089798441', '0', '5165450198704521651351654564564089798441'],
@@ -566,7 +566,7 @@ public function testMinus(string $a, string $b, string $r) : void
         self::assertBigIntegerEquals($r, BigInteger::of($a)->minus($b));
     }
 
-    public function providerMinus() : array
+    public static function providerMinus() : array
     {
         return [
             ['5165450198704521651351654564564089798441', '0', '5165450198704521651351654564564089798441'],
@@ -593,7 +593,7 @@ public function testMultipliedBy(string $a, $b, string $r) : void
         self::assertBigIntegerEquals($r, BigInteger::of($a)->multipliedBy($b));
     }
 
-    public function providerMultipliedBy() : array
+    public static function providerMultipliedBy() : array
     {
         return [
             ['123456789098765432101234567890987654321', '1', '123456789098765432101234567890987654321'],
@@ -637,7 +637,7 @@ public function testDividedBy(string $number, $divisor, string $expected) : void
         }
     }
 
-    public function providerDividedBy() : array
+    public static function providerDividedBy() : array
     {
         return [
             ['123456789098765432101234567890987654321', 1, '123456789098765432101234567890987654321'],
@@ -708,7 +708,7 @@ private function doTestDividedByWithRoundingMode(int $roundingMode, BigInteger $
         }
     }
 
-    public function providerDividedByWithRoundingMode() : array
+    public static function providerDividedByWithRoundingMode() : array
     {
         return [
             [RoundingMode::UP,  '3501',  '351',  '36',  '4'],
@@ -1226,7 +1226,7 @@ public function testQuotientAndRemainder(string $dividend, string $divisor, stri
         self::assertBigIntegerEquals($remainder, $r);
     }
 
-    public function providerQuotientAndRemainder() : array
+    public static function providerQuotientAndRemainder() : array
     {
         return [
             ['1', '123', '0', '1'],
@@ -1302,7 +1302,7 @@ public function testMod(string $dividend, string $divisor, string $expected) : v
         self::assertBigIntegerEquals($expected, BigInteger::of($dividend)->mod($divisor));
     }
 
-    public function providerMod() : array
+    public static function providerMod() : array
     {
         return [
             ['0', '1', '0'],
@@ -1399,7 +1399,7 @@ public function testModPow(string $base, string $exp, string $mod, string $expec
         self::assertBigIntegerEquals($expected, BigInteger::of($base)->modPow($exp, $mod));
     }
 
-    public function providerModPow() : array
+    public static function providerModPow() : array
     {
         return [
             ['0', '0', '1', '0'],
@@ -1476,7 +1476,7 @@ public function testModPowNegativeThrowsException(int $base, int $exp, int $mod)
         BigInteger::of($base)->modPow($exp, $mod);
     }
 
-    public function providerModPowNegativeThrowsException() : array
+    public static function providerModPowNegativeThrowsException() : array
     {
         return [
             [ 1,  1, -1],
@@ -1503,7 +1503,7 @@ public function testPower(string $number, int $exponent, string $expected) : voi
         self::assertBigIntegerEquals($expected, BigInteger::of($number)->power($exponent));
     }
 
-    public function providerPower() : array
+    public static function providerPower() : array
     {
         return [
             ['-3', 0, '1'],
@@ -1561,7 +1561,7 @@ public function testPowerWithInvalidExponentThrowsException(int $power) : void
         BigInteger::of(1)->power($power);
     }
 
-    public function providerPowerWithInvalidExponentThrowsException() : array
+    public static function providerPowerWithInvalidExponentThrowsException() : array
     {
         return [
             [-1],
@@ -1584,7 +1584,7 @@ public function testGcd(string $a, string $b, string $gcd) : void
         self::assertBigIntegerEquals($gcd, $a->gcd($b));
     }
 
-    public function providerGcd() : \Generator
+    public static function providerGcd() : \Generator
     {
         $tests = [
             ['0', '0', '0'],
@@ -1679,7 +1679,7 @@ public function testSqrt(string $number, string $sqrt) : void
         self::assertBigIntegerEquals($sqrt, $number->sqrt());
     }
 
-    public function providerSqrt() : array
+    public static function providerSqrt() : array
     {
         return [
             ['0', '0'],
@@ -2039,7 +2039,7 @@ public function testAbs(string $number, string $expected) : void
         self::assertBigIntegerEquals($expected, BigInteger::of($number)->abs());
     }
 
-    public function providerAbs() : array
+    public static function providerAbs() : array
     {
         return [
             ['0', '0'],
@@ -2059,7 +2059,7 @@ public function testNegated(string $number, string $expected) : void
         self::assertBigIntegerEquals($expected, BigInteger::of($number)->negated());
     }
 
-    public function providerNegated() : array
+    public static function providerNegated() : array
     {
         return [
             ['0', '0'],
@@ -2080,7 +2080,7 @@ public function testOr(string $a, string $b, string $c) : void
         self::assertBigIntegerEquals($c, BigInteger::of($a)->or($b));
     }
 
-    public function providerOr() : array
+    public static function providerOr() : array
     {
         return [
             ['-1', '-2', '-1'],
@@ -2152,7 +2152,7 @@ public function testAnd(string $a, string $b, string $c) : void
         self::assertBigIntegerEquals($c, BigInteger::of($a)->and($b));
     }
 
-    public function providerAnd() : array
+    public static function providerAnd() : array
     {
         return [
             ['-1', '-2', '-2'],
@@ -2229,7 +2229,7 @@ public function testXor(string $a, string $b, string $c) : void
         self::assertBigIntegerEquals($c, BigInteger::of($a)->xor($b));
     }
 
-    public function providerXor() : array
+    public static function providerXor() : array
     {
         return [
             ['-1', '-2', '1'],
@@ -2299,7 +2299,7 @@ public function testNot(string $number, string $expected) : void
         self::assertBigIntegerEquals($expected, BigInteger::of($number)->not());
     }
 
-    public function providerNot() : array
+    public static function providerNot() : array
     {
         return [
             ['-32769', '32768'],
@@ -2348,7 +2348,7 @@ public function testShiftedRight(string $a, int $b, string $c) : void
         self::assertBigIntegerEquals($c, BigInteger::of($a)->shiftedRight(- $b));
     }
 
-    public function providerShiftedLeft() : array
+    public static function providerShiftedLeft() : array
     {
         return [
             ['-1', 1, '-2'],
@@ -2504,7 +2504,7 @@ public function testGetBitLength(string $number, int $bitLength) : void
         self::assertSame($bitLength, BigInteger::of($number)->getBitLength());
     }
 
-    public function providerGetBitLength() : array
+    public static function providerGetBitLength() : array
     {
         return [
             ['-10141204801825835211973625643009', 104],
@@ -2581,7 +2581,7 @@ public function testGetLowestSetBit(string $number, int $lowestSetBit) : void
         self::assertSame($lowestSetBit, BigInteger::of($number)->getLowestSetBit());
     }
 
-    public function providerGetLowestSetBit() : array
+    public static function providerGetLowestSetBit() : array
     {
         return [
             ['-10', 1],
@@ -2638,7 +2638,7 @@ public function testIsOdd(string $number, bool $isOdd) : void
         self::assertSame($isOdd, BigInteger::of($number)->isOdd());
     }
 
-    public function providerIsOdd() : \Generator
+    public static function providerIsOdd() : \Generator
     {
         $tests = [
             ['123456789012345678900', false],
@@ -2671,7 +2671,7 @@ public function testTestBit(BigInteger $number, int $n, bool $expected) : void
         self::assertSame($expected, $number->testBit($n));
     }
 
-    public function providerTestBit() : \Generator
+    public static function providerTestBit() : \Generator
     {
         $base2BitsSetTests = [
             ['0', []],
@@ -2743,7 +2743,7 @@ public function testModInverse(string $x, string $m, string $expectedResult) : v
         self::assertSame($expectedResult, (string) $x->modInverse($m));
     }
 
-    public function providerModInverse() : array
+    public static function providerModInverse() : array
     {
         return [
             ['1', '1', '0'],
@@ -2775,7 +2775,7 @@ public function testModInverseThrows(string $x, string $m, string $expectedExcep
         $x->modInverse($m);
     }
 
-    public function providerModInverseThrows() : array
+    public static function providerModInverseThrows() : array
     {
         return [
             ['0', '0', DivisionByZeroException::class],
@@ -2861,7 +2861,7 @@ public function testIsGreaterThanOrEqualTo(string $a, string $b, int $c) : void
         self::assertSame($c >= 0, BigInteger::of($a)->isGreaterThanOrEqualTo($b));
     }
 
-    public function providerCompareTo() : array
+    public static function providerCompareTo() : array
     {
         return [
             ['123', '123',  0],
@@ -2970,7 +2970,7 @@ public function testIsPositiveOrZero($number, int $sign) : void
         self::assertSame($sign >= 0, BigInteger::of($number)->isPositiveOrZero());
     }
 
-    public function providerSign() : array
+    public static function providerSign() : array
     {
         return [
             [ 0,  0],
@@ -2998,7 +2998,7 @@ public function testToScale(string $number, int $scale, string $expected) : void
         self::assertBigDecimalEquals($expected, BigInteger::of($number)->toScale($scale));
     }
 
-    public function providerToScale() : array
+    public static function providerToScale() : array
     {
         return [
             ['12345678901234567890123456789', 0, '12345678901234567890123456789'],
@@ -3015,7 +3015,7 @@ public function testToInt(int $number) : void
         self::assertSame($number, BigInteger::of((string) $number)->toInt());
     }
 
-    public function providerToInt() : array
+    public static function providerToInt() : array
     {
         return [
             [PHP_INT_MIN],
@@ -3051,7 +3051,7 @@ public function testToFloat(string $value, float $float) : void
         self::assertSame($float, BigInteger::of($value)->toFloat());
     }
 
-    public function providerToFloat() : array
+    public static function providerToFloat() : array
     {
         return [
             ['0', 0.0],
@@ -3076,7 +3076,7 @@ public function testToBase(string $number, int $base, string $expected) : void
         self::assertSame($expected, BigInteger::of($number)->toBase($base));
     }
 
-    public function providerToBase() : \Generator
+    public static function providerToBase() : \Generator
     {
         $tests = [
             ['640998479760579495168036691627608949', 36, '110011001100110011001111'],
@@ -3176,7 +3176,7 @@ public function testToInvalidBaseThrowsException(int $base) : void
         BigInteger::of(0)->toBase($base);
     }
 
-    public function providerToInvalidBaseThrowsException() : array
+    public static function providerToInvalidBaseThrowsException() : array
     {
         return [
             [-2],
@@ -3197,9 +3197,9 @@ public function testFromArbitraryBase(string $base10, string $alphabet, string $
         self::assertBigIntegerEquals($base10, $number);
     }
 
-    public function providerFromArbitraryBase() : \Generator
+    public static function providerFromArbitraryBase() : \Generator
     {
-        foreach ($this->providerArbitraryBase() as [$base10, $alphabet, $baseN]) {
+        foreach (self::providerArbitraryBase() as [$base10, $alphabet, $baseN]) {
             yield [$base10, $alphabet, $baseN];
 
             // test with a number of leading "zeros"
@@ -3219,7 +3219,7 @@ public function testToArbitraryBase(string $base10, string $alphabet, string $ba
         self::assertSame($baseN, $actual);
     }
 
-    public function providerArbitraryBase() : array
+    public static function providerArbitraryBase() : array
     {
         $base7  = '0123456';
         $base8  = '01234567';
@@ -3316,7 +3316,7 @@ public function testFromArbitraryBaseWithInvalidNumber(string $number, string $a
         BigInteger::fromArbitraryBase($number, $alphabet);
     }
 
-    public function providerFromArbitraryBaseWithInvalidNumber() : array
+    public static function providerFromArbitraryBaseWithInvalidNumber() : array
     {
         return [
             ['', '01', 'The number cannot be empty.'],
@@ -3345,7 +3345,7 @@ public function testToArbitraryBaseWithInvalidAlphabet(string $alphabet) : void
         $number->toArbitraryBase($alphabet);
     }
 
-    public function providerArbitraryBaseWithInvalidAlphabet() : array
+    public static function providerArbitraryBaseWithInvalidAlphabet() : array
     {
         return [
             [''],
@@ -3372,9 +3372,9 @@ public function testFromBytes(string $byteStringHex, bool $signed, string $expec
         self::assertSame($expectedNumber, (string) $number);
     }
 
-    public function providerFromBytes() : Generator
+    public static function providerFromBytes() : Generator
     {
-        foreach ($this->providerToBytes() as [$expectedNumber, $signed, $byteStringHex]) {
+        foreach (self::providerToBytes() as [$expectedNumber, $signed, $byteStringHex]) {
             yield [$byteStringHex, $signed, $expectedNumber];
 
             // test with extra leading bits: these should return the same number
@@ -3398,7 +3398,7 @@ public function testToBytes(string $number, bool $signed, string $expectedByteSt
         self::assertSame($expectedByteStringHex, strtoupper(bin2hex($byteString)));
     }
 
-    public function providerToBytes() : array
+    public static function providerToBytes() : array
     {
         return [
             ['-549755813889', true, 'FF7FFFFFFFFF'],
@@ -3617,7 +3617,7 @@ public function testRandomBits(int $numBits, string $randomBytesHex, string $exp
         self::assertBigIntegerEquals($expectedNumber, $actualNumber);
     }
 
-    public function providerRandomBits() : array
+    public static function providerRandomBits() : array
     {
         return [
             [1, '00', '0'],
@@ -3707,7 +3707,7 @@ public function testRandomRange(string $min, string $max, array $randomBytesHex,
         self::assertBigIntegerEquals($expectedNumber, $actualNumber);
     }
 
-    public function providerRandomRange() : array
+    public static function providerRandomRange() : array
     {
         return [
             ['0', '1', ['00'], '0'],
diff --git a/tests/BigNumberTest.php b/tests/BigNumberTest.php
index efb6b67..b7b9656 100644
--- a/tests/BigNumberTest.php
+++ b/tests/BigNumberTest.php
@@ -32,7 +32,7 @@ public function testSum(array $values, string $expectedClass, string $expectedSu
         self::assertSame($expectedSum, (string) $sum);
     }
 
-    public function providerSum() : array
+    public static function providerSum() : array
     {
         return [
             [[-1], BigInteger::class, '-1'],
diff --git a/tests/BigRationalTest.php b/tests/BigRationalTest.php
index 5ebb0c1..9b045e7 100644
--- a/tests/BigRationalTest.php
+++ b/tests/BigRationalTest.php
@@ -31,7 +31,7 @@ public function testNd(string $numerator, string $denominator, $n, $d) : void
         self::assertBigRationalInternalValues($numerator, $denominator, $rational);
     }
 
-    public function providerNd() : array
+    public static function providerNd() : array
     {
         return [
             ['7', '1', '7', 1],
@@ -61,7 +61,7 @@ public function testOf(string $numerator, string $denominator, string $string) :
         self::assertBigRationalInternalValues($numerator, $denominator, $rational);
     }
 
-    public function providerOf() : array
+    public static function providerOf() : array
     {
         return [
             ['123', '456', '123/456'],
@@ -93,7 +93,7 @@ public function testOfInvalidString(string $string) : void
         BigRational::of($string);
     }
 
-    public function providerOfInvalidString() : array
+    public static function providerOfInvalidString() : array
     {
         return [
             ['123/-456'],
@@ -145,7 +145,7 @@ public function testMin(array $values, string $min) : void
         self::assertBigRationalEquals($min, BigRational::min(... $values));
     }
 
-    public function providerMin() : array
+    public static function providerMin() : array
     {
         return [
             [['1/2', '1/4', '1/3'], '1/4'],
@@ -172,7 +172,7 @@ public function testMax(array $values, string $max) : void
         self::assertBigRationalEquals($max, BigRational::max(... $values));
     }
 
-    public function providerMax() : array
+    public static function providerMax() : array
     {
         return [
             [['-5532146515641651651321321064580/32453', '-1/2', '-1/99'], '-1/99'],
@@ -202,7 +202,7 @@ public function testSum(array $values, string $sum) : void
         self::assertBigRationalEquals($sum, BigRational::sum(... $values));
     }
 
-    public function providerSum() : array
+    public static function providerSum() : array
     {
         return [
             [['-5532146515641651651321321064580/32453', '-1/2', '-1/99'], '-1095365010097047026961621574064593/6425694'],
@@ -241,7 +241,7 @@ public function testQuotientAndRemainder($rational, string $quotient, string $re
         self::assertBigIntegerEquals($remainder, $quotientAndRemainder[1]);
     }
 
-    public function providerQuotientAndRemainder() : array
+    public static function providerQuotientAndRemainder() : array
     {
         return [
             ['1000/3', '333', '1'],
@@ -263,7 +263,7 @@ public function testPlus(string $rational, $plus, string $expected) : void
         self::assertBigRationalEquals($expected, BigRational::of($rational)->plus($plus));
     }
 
-    public function providerPlus() : array
+    public static function providerPlus() : array
     {
         return [
             ['123/456', 1, '579/456'],
@@ -288,7 +288,7 @@ public function testMinus(string $rational, string $minus, string $expected) : v
         self::assertBigRationalEquals($expected, BigRational::of($rational)->minus($minus));
     }
 
-    public function providerMinus() : array
+    public static function providerMinus() : array
     {
         return [
             ['123/456', '1', '-333/456'],
@@ -311,7 +311,7 @@ public function testMultipliedBy(string $rational, string $minus, string $expect
         self::assertBigRationalEquals($expected, BigRational::of($rational)->multipliedBy($minus));
     }
 
-    public function providerMultipliedBy() : array
+    public static function providerMultipliedBy() : array
     {
         return [
             ['123/456', '1', '123/456'],
@@ -336,7 +336,7 @@ public function testDividedBy(string $rational, string $minus, string $expected)
         self::assertBigRationalEquals($expected, BigRational::of($rational)->dividedBy($minus));
     }
 
-    public function providerDividedBy() : array
+    public static function providerDividedBy() : array
     {
         return [
             ['123/456', '1', '123/456'],
@@ -361,7 +361,7 @@ public function testPower(string $number, int $exponent, string $expected) : voi
         self::assertBigRationalEquals($expected, BigRational::of($number)->power($exponent));
     }
 
-    public function providerPower() : array
+    public static function providerPower() : array
     {
         return [
             ['-3',   0, '1'],
@@ -421,7 +421,7 @@ public function testReciprocal(string $rational, string $expected) : void
         self::assertBigRationalEquals($expected, BigRational::of($rational)->reciprocal());
     }
 
-    public function providerReciprocal() : array
+    public static function providerReciprocal() : array
     {
         return [
             ['1', '1'],
@@ -450,7 +450,7 @@ public function testAbs(string $rational, string $expected) : void
         self::assertBigRationalEquals($expected, BigRational::of($rational)->abs());
     }
 
-    public function providerAbs() : array
+    public static function providerAbs() : array
     {
         return [
             ['0', '0'],
@@ -473,7 +473,7 @@ public function testNegated(string $rational, string $expected) : void
         self::assertBigRationalEquals($expected, BigRational::of($rational)->negated());
     }
 
-    public function providerNegated() : array
+    public static function providerNegated() : array
     {
         return [
             ['0', '0'],
@@ -497,7 +497,7 @@ public function testSimplified(string $rational, string $expected) : void
         self::assertBigRationalEquals($expected, BigRational::of($rational)->simplified());
     }
 
-    public function providerSimplified() : array
+    public static function providerSimplified() : array
     {
         return [
             ['0', '0'],
@@ -588,7 +588,7 @@ public function testIsGreaterThanOrEqualTo(string $a, $b, int $cmp) : void
         self::assertSame($cmp >= 0, BigRational::of($a)->isGreaterThanOrEqualTo($b));
     }
 
-    public function providerCompareTo() : array
+    public static function providerCompareTo() : array
     {
         return [
             ['-1', '1/2', -1],
@@ -685,7 +685,7 @@ public function testIsPositiveOrZero(string $number, int $sign) : void
         self::assertSame($sign >= 0, BigRational::of($number)->isPositiveOrZero());
     }
 
-    public function providerSign() : array
+    public static function providerSign() : array
     {
         return [
             ['0', 0],
@@ -718,7 +718,7 @@ public function testToBigDecimal(string $number, ?string $expected) : void
         }
     }
 
-    public function providerToBigDecimal() : \Generator
+    public static function providerToBigDecimal() : \Generator
     {
         $tests = [
             ['1', '1'],
@@ -831,7 +831,7 @@ public function testToScale(string $number, int $scale, int $roundingMode, strin
         }
     }
 
-    public function providerToScale() : array
+    public static function providerToScale() : array
     {
         return [
             ['1/8', 3, RoundingMode::UNNECESSARY, '0.125'],
@@ -855,7 +855,7 @@ public function testToInt($rational, int $integer) : void
         self::assertSame($integer, BigRational::of($rational)->toInt());
     }
 
-    public function providerToInt() : array
+    public static function providerToInt() : array
     {
         return [
             [PHP_INT_MAX, PHP_INT_MAX],
@@ -882,7 +882,7 @@ public function testToIntThrowsException(string $number) : void
         BigRational::of($number)->toInt();
     }
 
-    public function providerToIntThrowsException() : array
+    public static function providerToIntThrowsException() : array
     {
         return [
             ['-999999999999999999999999999999'],
@@ -935,7 +935,7 @@ public function testToFloat(string $value, float $float) : void
         self::assertSame($float, BigRational::of($value)->toFloat());
     }
 
-    public function providerToFloat() : array
+    public static function providerToFloat() : array
     {
         return [
             ['0', 0.0],
@@ -960,7 +960,7 @@ public function testToString(string $numerator, string $denominator, string $exp
         self::assertBigRationalEquals($expected, BigRational::nd($numerator, $denominator));
     }
 
-    public function providerToString() : array
+    public static function providerToString() : array
     {
         return [
             ['-1', '1', '-1'],
diff --git a/tests/Internal/Calculator/NativeCalculatorTest.php b/tests/Internal/Calculator/NativeCalculatorTest.php
index 245bdaa..da66764 100644
--- a/tests/Internal/Calculator/NativeCalculatorTest.php
+++ b/tests/Internal/Calculator/NativeCalculatorTest.php
@@ -21,7 +21,7 @@ public function testAdd(string $a, string $b, string $expectedValue) : void
         self::assertSame($expectedValue, $nativeCalculator->add($a, $b));
     }
 
-    public function providerAdd() : array
+    public static function providerAdd() : array
     {
         return [
             ['0', '1234567891234567889999999', '1234567891234567889999999'],
@@ -43,7 +43,7 @@ public function testMul(string $a, string $b, string $expectedValue) : void
         self::assertSame($expectedValue, $nativeCalculator->mul($a, $b));
     }
 
-    public function providerMul() : array
+    public static function providerMul() : array
     {
         return [
             ['0', '0', '0'],
@@ -70,7 +70,7 @@ public function testPow(string $a, int $b, string $expectedValue) : void
         self::assertSame($expectedValue, $nativeCalculator->pow($a, $b));
     }
 
-    public function providerPow() : array
+    public static function providerPow() : array
     {
         return [
             ['123456789012345678901234567890', 0, '1'],