diff --git a/programmers/없는 숫자 더하기/solution.java b/programmers/없는 숫자 더하기/solution.java
new file mode 100644
index 0000000..ab03da9
--- /dev/null
+++ b/programmers/없는 숫자 더하기/solution.java	
@@ -0,0 +1,15 @@
+// [문제 링크]: https://school.programmers.co.kr/learn/courses/30/lessons/86051
+
+import java.util.Arrays;
+class Solution {
+    public int increaseSum(){
+        int first = 1;
+        int last = 9;
+        return (first+last)*last/2;
+    }
+    public int solution(int[] numbers) {
+        int answer = increaseSum();
+        int arrayS = Arrays.stream(numbers).sum();
+        return answer-arrayS;
+    }
+}
\ No newline at end of file