diff --git "a/JHLEE325/202511/21 BOJ G3 \353\202\230\353\250\270\354\247\200 \355\225\251.md" "b/JHLEE325/202511/21 BOJ G3 \353\202\230\353\250\270\354\247\200 \355\225\251.md"
new file mode 100644
index 00000000..94865dd3
--- /dev/null
+++ "b/JHLEE325/202511/21 BOJ G3 \353\202\230\353\250\270\354\247\200 \355\225\251.md"	
@@ -0,0 +1,36 @@
+```java
+import java.io.*;
+import java.util.*;
+
+public class Main {
+    public static void main(String[] args) throws Exception {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        StringTokenizer st = new StringTokenizer(br.readLine());
+
+        int N = Integer.parseInt(st.nextToken());
+        int M = Integer.parseInt(st.nextToken());
+
+        long[] count = new long[M];
+        long answer = 0;
+
+        long prefix = 0;
+
+        st = new StringTokenizer(br.readLine());
+        for (int i = 0; i < N; i++) {
+            prefix = (prefix + Integer.parseInt(st.nextToken())) % M;
+            count[(int) prefix]++;
+        }
+
+        answer += count[0];
+
+        for (int i = 0; i < M; i++) {
+            long c = count[i];
+            if (c >= 2) {
+                answer += (c * (c - 1)) / 2;
+            }
+        }
+
+        System.out.println(answer);
+    }
+}
+```