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 84c04f2..706fc7a 100644
--- a/app/src/main/java/htw/berlin/prog2/ha1/Calculator.java
+++ b/app/src/main/java/htw/berlin/prog2/ha1/Calculator.java
@@ -31,7 +31,7 @@ public String readScreen() {
     public void pressDigitKey(int digit) {
         if(digit > 9 || digit < 0) throw new IllegalArgumentException();
 
-        if(screen.equals("0") || latestValue == Double.parseDouble(screen)) screen = "";
+        if(screen.equals("0")) screen = "";
 
         screen = screen + digit;
     }
@@ -57,11 +57,17 @@ public void pressClearKey() {
      * Rechner in den passenden Operationsmodus versetzt.
      * Beim zweiten Drücken nach Eingabe einer weiteren Zahl wird direkt des aktuelle Zwischenergebnis
      * auf dem Bildschirm angezeigt. Falls hierbei eine Division durch Null auftritt, wird "Error" angezeigt.
+     * Diese Methode ermöglicht es dem Benutzer, mehrere aufeinanderfolgende Berechnungen durchzuführen,
+     * indem sie das Zwischenergebnis berechnet, bevor eine neue Operation eingegeben wird.
      * @param operation "+" für Addition, "-" für Substraktion, "x" für Multiplikation, "/" für Division
      */
     public void pressBinaryOperationKey(String operation)  {
+        if (!latestOperation.isEmpty()) {
+            pressEqualsKey();
+        }
         latestValue = Double.parseDouble(screen);
         latestOperation = operation;
+        screen = "0";
     }
 
     /**
@@ -82,6 +88,7 @@ public void pressUnaryOperationKey(String operation) {
         };
         screen = Double.toString(result);
         if(screen.equals("NaN")) screen = "Error";
+        if(screen.endsWith(".0")) screen = screen.substring(0, screen.length() - 2);
         if(screen.contains(".") && screen.length() > 11) screen = screen.substring(0, 10);
 
     }
@@ -118,7 +125,7 @@ public void pressNegativeKey() {
      * und das Ergebnis direkt angezeigt.
      */
     public void pressEqualsKey() {
-        var result = switch(latestOperation) {
+        double result = switch(latestOperation) {
             case "+" -> latestValue + Double.parseDouble(screen);
             case "-" -> latestValue - Double.parseDouble(screen);
             case "x" -> latestValue * Double.parseDouble(screen);
@@ -130,4 +137,5 @@ public void pressEqualsKey() {
         if(screen.endsWith(".0")) screen = screen.substring(0,screen.length()-2);
         if(screen.contains(".") && screen.length() > 11) screen = screen.substring(0, 10);
     }
+
 }
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 ddff0da..f018b15 100644
--- a/app/src/test/java/htw/berlin/prog2/ha1/CalculatorTest.java
+++ b/app/src/test/java/htw/berlin/prog2/ha1/CalculatorTest.java
@@ -88,7 +88,60 @@ void testMultipleDecimalDots() {
         assertEquals(expected, actual);
     }
 
+    @Test
+    @DisplayName("should display result after subtracting two positive multi-digit numbers")
+    void testPositiveSubtraction() {
+        Calculator calc = new Calculator();
+
+        calc.pressDigitKey(5);
+        calc.pressDigitKey(0);
+        calc.pressBinaryOperationKey("-");
+        calc.pressDigitKey(2);
+        calc.pressDigitKey(0);
+        calc.pressEqualsKey();
+
+        String expected = "30";
+        String actual = calc.readScreen();
+
+        assertEquals(expected, actual);
+    }
+
+    @Test
+    @DisplayName("should display result after calculating three positive multi-digit numbers")
+    void testCalculateThreeNumbers() {
+        Calculator calc = new Calculator();
+
+        calc.pressDigitKey(7);
+        calc.pressDigitKey(7);
+        calc.pressBinaryOperationKey("-");
+        calc.pressDigitKey(7);
+        calc.pressDigitKey(9);
+        calc.pressBinaryOperationKey("+");
+        calc.pressDigitKey(8);
+        calc.pressDigitKey(0);
+        calc.pressEqualsKey();
+
+        String expected = "78";
+        String actual = calc.readScreen();
+
+        assertEquals(expected, actual);
+    }
+
+    @Test
+    @DisplayName("should display percentage of a multi-digit number")
+    void testPercentageCalculation() {
+        Calculator calc = new Calculator();
+
+        calc.pressDigitKey(2);
+        calc.pressDigitKey(0);
+        calc.pressDigitKey(0);
+        calc.pressUnaryOperationKey("%");
+
+        String expected = "2";
+        String actual = calc.readScreen();
+
+        assertEquals(expected, actual);
+    }
 
-    //TODO hier weitere Tests erstellen
 }