diff --git a/Luogu/problem/P4942/P4942.cpp b/Luogu/problem/P4942/P4942.cpp
new file mode 100644
index 00000000..34fd3b5d
--- /dev/null
+++ b/Luogu/problem/P4942/P4942.cpp
@@ -0,0 +1,16 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+
+int t;
+long long l, r, c;
+
+int main() {
+    cin >> t;
+    while (t--) {
+        cin >> l >> r;
+        c = (r - l + 1) % 9;
+        cout << (c * (l % 9) % 9 + c * (c - 1) % 9 * 5 % 9) % 9 << endl;
+    }
+    return 0;
+}