diff --git a/c05_expression/min_sec.c b/c05_expression/min_sec.c
new file mode 100644
index 0000000..b3f0362
--- /dev/null
+++ b/c05_expression/min_sec.c
@@ -0,0 +1,24 @@
+#include <stdio.h>
+
+#define SEC_PER_MIN 60
+
+int main(void)
+{
+    int sec, min, left;
+
+    printf("Convert seconds to minuts and seconds!\n");
+    printf("Enter the number of seconds (<=0 to quit):\n");
+    scanf("%d", &sec);
+
+    while (sec > 0)
+    {
+        min = sec / SEC_PER_MIN;
+        left = sec % SEC_PER_MIN;
+        printf("%d seconds = %d:%d\n", sec, min, left);
+        printf("Enter next value (<0 to quite):\n");
+        scanf("%d", &sec);
+    }
+    printf("Done!\n");
+
+    return 0;
+}
\ No newline at end of file