diff --git a/c05_expression/squares.c b/c05_expression/squares.c
new file mode 100644
index 0000000..96c4aa1
--- /dev/null
+++ b/c05_expression/squares.c
@@ -0,0 +1,15 @@
+/* squares.c - 计算1～20的平方 */
+#include <stdio.h>
+
+int main(void)
+{
+    int num = 1;
+
+    while (num < 21)
+    {
+        printf("%4d\t%6d\n", num, num * num);
+        num = num + 1;
+    }
+    
+    return 0;
+}
\ No newline at end of file