diff --git a/app/src/main/java/htw/berlin/prog2/ha1/Calculator.java b/app/src/main/java/htw/berlin/prog2/ha1/Calculator.java
index 84c04f21..9075a1b2 100644
--- a/app/src/main/java/htw/berlin/prog2/ha1/Calculator.java
+++ b/app/src/main/java/htw/berlin/prog2/ha1/Calculator.java
@@ -13,6 +13,7 @@ public class Calculator {
     private double latestValue;
 
     private String latestOperation = "";
+    private boolean pressedClearEntryKey = false;
 
     /**
      * @return den aktuellen Bildschirminhalt als String
@@ -45,9 +46,16 @@ public void pressDigitKey(int digit) {
      * im Ursprungszustand ist.
      */
     public void pressClearKey() {
-        screen = "0";
+        if (!pressedClearEntryKey) {
+            screen = "0";
+            pressedClearEntryKey = true;
+        } else if (pressedClearEntryKey) {
+            screen = "0";
         latestOperation = "";
         latestValue = 0.0;
+        pressedClearEntryKey = false;
+
+        }
     }
 
     /**
@@ -94,7 +102,7 @@ public void pressUnaryOperationKey(String operation) {
      * Beim zweimaligem Drücken, oder wenn bereits ein Trennzeichen angezeigt wird, passiert nichts.
      */
     public void pressDotKey() {
-        if(!screen.contains(".")) screen = screen + ".";
+        if(!screen.contains(".") && screen.length() < 9 ) screen = screen + ".";
     }
 
     /**
diff --git a/app/src/test/java/htw/berlin/prog2/ha1/CalculatorTest.java b/app/src/test/java/htw/berlin/prog2/ha1/CalculatorTest.java
index ddff0daf..36b73967 100644
--- a/app/src/test/java/htw/berlin/prog2/ha1/CalculatorTest.java
+++ b/app/src/test/java/htw/berlin/prog2/ha1/CalculatorTest.java
@@ -90,5 +90,69 @@ void testMultipleDecimalDots() {
 
 
     //TODO hier weitere Tests erstellen
+    @Test
+    @DisplayName("should display result after adding two positive single-digit numbers")
+    void testSimpleAddition() {
+        Calculator calc = new Calculator();
+
+        calc.pressDigitKey(3);
+        calc.pressBinaryOperationKey("+");
+        calc.pressDigitKey(7);
+        calc.pressEqualsKey();
+
+        String expected = "10";
+        String actual = calc.readScreen();
+
+
+        assertEquals(expected, actual);
+    }
+
+    @Test
+    @DisplayName("")
+    void test() {
+        Calculator calc = new Calculator();
+
+        calc.pressDigitKey(3);
+        calc.pressDigitKey(3);
+        calc.pressDigitKey(3);
+        calc.pressDigitKey(3);
+        calc.pressDigitKey(3);
+        calc.pressDigitKey(3);
+        calc.pressDigitKey(3);
+        calc.pressDigitKey(3);
+        calc.pressDigitKey(3);
+        calc.pressDotKey();
+
+
+        String expected = "333333333";
+        String actual = calc.readScreen();
+
+
+        assertEquals(expected, actual);
+    }
+
+    @Test
+    @DisplayName("")
+    public void pressClearKey() {
+        Calculator calc = new Calculator();
+
+        calc.pressDigitKey(3);
+        calc.pressBinaryOperationKey("+");
+        calc.pressDigitKey(7);
+        calc.pressClearKey();
+        calc.pressDigitKey(3);
+        calc.pressEqualsKey();
+
+
+        String expected = "6";
+        String actual = calc.readScreen();
+
+
+        assertEquals(expected, actual);
+    }
 }
 
+
+
+
+