diff --git a/src/main/java/tdd/setup/Calculator.java b/src/main/java/tdd/setup/Calculator.java
index 171f6d6..c4dd77a 100644
--- a/src/main/java/tdd/setup/Calculator.java
+++ b/src/main/java/tdd/setup/Calculator.java
@@ -1,29 +1,27 @@
 package tdd.setup;
+import java.util.Scanner;
 
 // behaviour inspired by https://www.online-calculator.com/
 public class Calculator {
 
-    private String screen = "0";
+    private String screen = "";
 
     private double latestValue;
 
     private String latestOperation = "";
 
-    public String readScreen() {
+    public String readScreen()
+    {
         return screen;
     }
-    public void pressDigitKey(int digit) {
+    public void pressDigitKey(int digit)
+    {
         if(digit > 9 || digit < 0) throw new IllegalArgumentException();
-
-        if(latestOperation.isEmpty()) {
             screen = screen + digit;
-        } else {
-            latestValue = Double.parseDouble(screen);
-            screen = Integer.toString(digit);
-        }
     }
 
-    public void pressClearKey() {
+    public void pressClearKey()
+    {
         screen = "0";
         latestOperation = "";
         latestValue = 0.0;
@@ -31,6 +29,8 @@ public void pressClearKey() {
 
     public void pressOperationKey(String operation)  {
         latestOperation = operation;
+        latestValue = Double.parseDouble(screen);
+        screen = "";
     }
 
     public void pressDotKey() {
@@ -41,6 +41,8 @@ public void pressNegative() {
         screen = screen.startsWith("-") ? screen.substring(1) : "-" + screen;
     }
 
+
+
     public void pressEquals() {
         var result = switch(latestOperation) {
             case "+" -> latestValue + Double.parseDouble(screen);
@@ -53,3 +55,5 @@ public void pressEquals() {
         if(screen.endsWith(".0")) screen = screen.substring(0,screen.length()-2);
     }
 }
+
+//hallo
\ No newline at end of file
diff --git a/src/test/java/tdd/setup/CalculatorTest.java b/src/test/java/tdd/setup/CalculatorTest.java
index 3bf16e9..b8921d0 100644
--- a/src/test/java/tdd/setup/CalculatorTest.java
+++ b/src/test/java/tdd/setup/CalculatorTest.java
@@ -16,4 +16,51 @@ void calculatorCanDoTwoPlusTwo() {
         calc.pressEquals();
         assertEquals("4", calc.readScreen());
     }
+
+    //successful
+    @Test
+    @DisplayName("should display result after multiplying two positive numbers")
+    void calculatorCanDoTwoTimesFour()
+    {
+        Calculator calc = new Calculator();
+        calc.pressDigitKey(2);
+        calc.pressOperationKey("x");
+        calc.pressDigitKey(4);
+        calc.pressEquals();
+        assertEquals("8", calc.readScreen());
+        System.out.println(calc.readScreen());
+    }
+
+
+
+    //fail
+    @Test
+    @DisplayName("should display result after addition with dot ")
+    void calculatorCanDoAdditionWithDot()
+    {
+        Calculator calc = new Calculator();
+
+        calc.pressDigitKey(5);
+        calc.pressDotKey();
+        calc.pressDigitKey(2);
+        calc.pressOperationKey("+");
+        calc.pressDigitKey(3);
+        calc.pressDotKey();
+        calc.pressDigitKey(5);
+        calc.pressEquals();
+        assertEquals("8.7", calc.readScreen());
+        System.out.println(calc.readScreen());
+    }
+
+    @Test
+    @DisplayName("should display number negative")
+    void calculatorCanDoNegative()
+    {
+        Calculator calc = new Calculator();
+        calc.pressDigitKey(3);
+        calc.pressNegative();
+        assertEquals("-3", calc.readScreen());
+        System.out.println(calc.readScreen());
+    }
+
 }