diff --git a/src/main/java/arytmetyka/Kalkulator.java b/src/main/java/arytmetyka/Kalkulator.java
index cf196f0..1b21f67 100644
--- a/src/main/java/arytmetyka/Kalkulator.java
+++ b/src/main/java/arytmetyka/Kalkulator.java
@@ -19,5 +19,11 @@ public int div(int x, int y) {
         }
         return x / y;
     }
+    public int silnia(int x) {
+        int res = 1;
+        for(int i=1; i<x; i++)
+            res *=i;
+        return res;
+    }
 
 }
diff --git a/src/test/java/arytmetyka/KalkulatorTest.java b/src/test/java/arytmetyka/KalkulatorTest.java
index b0d02d3..1b6c808 100644
--- a/src/test/java/arytmetyka/KalkulatorTest.java
+++ b/src/test/java/arytmetyka/KalkulatorTest.java
@@ -30,6 +30,11 @@ public void dodawanieTest() {
         assertThat(testee.add(2, -2)).isEqualTo(0);
     }
 
+    @Test
+    public void silniaTest() {
+        assertThat(testee.silnia(4)).isEqualTo(24);
+    }
+
     @Test(expected = ArithmeticException.class)
     public void dzieleniePrzezZeroTest() {
         testee.div(2, 0);