Update 2019-11-07-numerics.md (#165)

Typo: "logarithmetic"

_posts/2019-11-07-numerics.md

@@ -32,7 +32,7 @@ The `RealFunctions` protocol refines `ElementaryFunctions`, and adds operations
 - `hypot`, which computes `sqrt(x*x + y*y)` without intermediate overflow or underflow.
 - `erf` and `erfc`, the [error function][ErrorFunction] and its complement.
 - Exponential functions: `exp2` and `exp10`
-- Logarithmetic functions: `log2` and `log10`
+- Logarithmic functions: `log2` and `log10`
 - Gamma functions: `gamma`, `logGamma`, and `signGamma`, which evaluate the [gamma function][GammaFunction], its logarithm, and its sign.
 
 The protocol that you will use most often is `Real`, which describes a floating-point type equipped with the full set of basic math functions.