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..898d25ef 100644
--- a/app/src/main/java/htw/berlin/prog2/ha1/Calculator.java
+++ b/app/src/main/java/htw/berlin/prog2/ha1/Calculator.java
@@ -60,8 +60,10 @@ public void pressClearKey() {
      * @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;
+
     }
 
     /**
@@ -110,7 +112,7 @@ public void pressNegativeKey() {
 
     /**
      * Empfängt den Befehl der gedrückten "="-Taste.
-     * Wurde zuvor keine Operationstaste gedrückt, passiert nichts.
+     * Wurde zuvor keine Operationstaste gedrückt, wird die Eingegebene Zahl auf dem Bildschirm ausgegeben.
      * Wurde zuvor eine binäre Operationstaste gedrückt und zwei Operanden eingegeben, wird das
      * Ergebnis der Operation angezeigt. Falls hierbei eine Division durch Null auftritt, wird "Error" angezeigt.
      * Wird die Taste weitere Male gedrückt (ohne andere Tasten dazwischen), so wird die letzte
@@ -118,16 +120,32 @@ public void pressNegativeKey() {
      * und das Ergebnis direkt angezeigt.
      */
     public void pressEqualsKey() {
-        var result = switch(latestOperation) {
-            case "+" -> latestValue + Double.parseDouble(screen);
-            case "-" -> latestValue - Double.parseDouble(screen);
-            case "x" -> latestValue * Double.parseDouble(screen);
-            case "/" -> latestValue / Double.parseDouble(screen);
-            default -> throw new IllegalArgumentException();
-        };
-        screen = Double.toString(result);
-        if(screen.equals("Infinity")) screen = "Error";
-        if(screen.endsWith(".0")) screen = screen.substring(0,screen.length()-2);
-        if(screen.contains(".") && screen.length() > 11) screen = screen.substring(0, 10);
+        if (!latestOperation.isEmpty()) {
+            var result = switch (latestOperation) {
+                case "+" -> latestValue + Double.parseDouble(screen);
+                case "-" -> latestValue - Double.parseDouble(screen);
+                case "x" -> latestValue * Double.parseDouble(screen);
+                case "/" -> latestValue / Double.parseDouble(screen);
+                case "" -> Double.parseDouble(screen);
+                default -> throw new IllegalArgumentException();
+
+
+            };
+            screen = Double.toString(result);
+            if (screen.equals("Infinity")) screen = "Error";
+            if (screen.endsWith(".0")) screen = screen.substring(0, screen.length() - 2);
+            if (screen.contains(".") && screen.length() > 11) screen = screen.substring(0, 10);
+        } else {
+            return;
+        }
+
+
     }
+
+
+
 }
+
+
+
+
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..6ca259f2 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 multiplying two numbers")
+    void testMultiplication() {
+        Calculator calc = new Calculator();
+
+        calc.pressDigitKey(3);
+        calc.pressBinaryOperationKey("x");
+        calc.pressDigitKey(4);
+        calc.pressEqualsKey();
+
+        String expected = "12";
+        String actual = calc.readScreen();
+
+        assertEquals(expected, actual);
+    }
+
+// Teilaufgabe 2.1
+@Test
+@DisplayName("should display latest number after pressing equals")
+void testEqualKey() {
+    Calculator calc = new Calculator();
+    calc.pressDigitKey(5);
+    calc.pressEqualsKey();
+
+    String expected = "5";
+    String actual = calc.readScreen();
+
+    assertEquals(expected, actual);
+
+}
+    // Teiaufgabe 2.2
+
+    @Test
+    @DisplayName("should display result after adding multiple positive multi-digit numbers")
+    void testPositiveAdditionWithMultipleDigits() {
+        Calculator calc = new Calculator();
+
+        calc.pressDigitKey(7);
+        calc.pressDigitKey(0);
+        calc.pressBinaryOperationKey("+");
+        calc.pressDigitKey(1);
+        calc.pressDigitKey(0);
+        calc.pressBinaryOperationKey("+");
+        calc.pressDigitKey(7);
+        calc.pressDigitKey(0);
+        calc.pressEqualsKey();
+
+        String expected = "150";
+        String actual = calc.readScreen();
+
+        assertEquals(expected, actual);
+    }
 
     //TODO hier weitere Tests erstellen
+
 }