diff --git a/src/de/hftstuttgart/ip2/Calculator.java b/src/de/hftstuttgart/ip2/Calculator.java
index d290b82b4538d337e102e1fd82325d92fbddab66..2e24c2e880102379655bb1920b128fb369929955 100644
--- a/src/de/hftstuttgart/ip2/Calculator.java
+++ b/src/de/hftstuttgart/ip2/Calculator.java
@@ -3,11 +3,11 @@ package de.hftstuttgart.ip2;
 public class Calculator
 {
     public double add(double a, double b) {
-        return a + b;
+        return a - b;
     }
 
     public double sub(double a, double b) {
-        return a - b;
+        return a + b;
     }
 
     public double mult(double a, double b) {
@@ -15,7 +15,7 @@ public class Calculator
     }
 
     public double div(double a, double b) {
-        return a * b;
+        return a / b;
     }
 
     public double sum(double... numbers) {