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AlgoLeadMe · Feb 18, 2024 · 7ae5938 · 7ae5938
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diff --git a/miniron-v/README.md b/miniron-v/README.md
@@ -14,6 +14,9 @@
 | 10차시 | 2024.01.28 |  그래프  | [토마토](https://www.acmicpc.net/problem/7569)  | [#38](https://github.com/AlgoLeadMe/AlgoLeadMe-5/pull/38) |
 | 번외 - 10 | 2024.01.30 |  그래프  | [하이퍼 토마토](https://www.acmicpc.net/problem/17114)  | [#42](https://github.com/AlgoLeadMe/AlgoLeadMe-5/pull/42) |
 | 11차시 | 2024.01.31 |  브루트포스  | [감소하는 수](https://www.acmicpc.net/problem/1038)  | [#43](https://github.com/AlgoLeadMe/AlgoLeadMe-5/pull/43) |
-| 12차시 | 2024.01.31 |  DP  | [점프 점프](https://www.acmicpc.net/problem/11060)  | [#48](https://github.com/AlgoLeadMe/AlgoLeadMe-5/pull/48) |
-| 13차시 | 2024.01.31 |  DP  | [퇴사 2](https://www.acmicpc.net/problem/15486)  | [#50](https://github.com/AlgoLeadMe/AlgoLeadMe-5/pull/50) |
+| 12차시 | 2024.02.03 |  DP  | [점프 점프](https://www.acmicpc.net/problem/11060)  | [#48](https://github.com/AlgoLeadMe/AlgoLeadMe-5/pull/48) |
+| 13차시 | 2024.02.06 |  DP  | [퇴사 2](https://www.acmicpc.net/problem/15486)  | [#50](https://github.com/AlgoLeadMe/AlgoLeadMe-5/pull/50) |
+| 14차시 | 2024.02.11 |  그래프, DP  | [ACM Craft](https://www.acmicpc.net/problem/1005)  | [#53](https://github.com/AlgoLeadMe/AlgoLeadMe-5/pull/53) |
+| 15차시 | 2024.02.15 |  DP, 큰 수 연산  | [타일링](https://www.acmicpc.net/problem/1793)  | [#56](https://github.com/AlgoLeadMe/AlgoLeadMe-5/pull/56) |
+| 16차시 | 2024.02.18 |  수학  | [합](https://www.acmicpc.net/problem/1081)  | [#61](https://github.com/AlgoLeadMe/AlgoLeadMe-5/pull/61) |
 ---
diff --git a/miniron-v/수학/1081-합.cpp b/miniron-v/수학/1081-합.cpp
@@ -0,0 +1,36 @@
+#include <iostream>
+
+long long gaussSum(long long k) {
+	if (k % 2 == 0) {
+		return (k / 2) * (k + 1);
+	}
+
+	return ((k + 1) / 2) * k;
+}
+
+long long getSumOfPlace(long long n) {
+	if (n < 1) {
+		return 0;
+	}
+
+	long long answer = gaussSum(n);
+
+	long long d = 10;
+	while ((n / d) > 0) {
+		long long q = n / d;
+		long long r = n % d;
+
+		answer -= 9 * (gaussSum(q - 1) * d + q * (r + 1));
+
+		d *= 10;
+	}
+
+	return answer;
+}
+
+int main() {
+	long long l, u;
+	std::cin >> l >> u;
+
+	std::cout << getSumOfPlace(u) - getSumOfPlace(l - 1);
+}