diff --git a/tag4a2.c b/tag4a2.c
new file mode 100644
index 0000000..ca18592
--- /dev/null
+++ b/tag4a2.c
@@ -0,0 +1,14 @@
+#include <stdio.h>
+
+double square_to (double *a) {
+	*a = *a * *a;
+	printf("Das Quadrat ist %f .\n", *a);
+	return *a;
+}
+
+int main() {
+	
+	double u=7;
+	printf("Das Ergebnis ist: %f .\n", square_to(&u));
+	return 0;
+}