diff --git a/src/main/java/tdd/setup/Calculator.java b/src/main/java/tdd/setup/Calculator.java
index 171f6d6..0be3c90 100644
--- a/src/main/java/tdd/setup/Calculator.java
+++ b/src/main/java/tdd/setup/Calculator.java
@@ -3,7 +3,7 @@
 // behaviour inspired by https://www.online-calculator.com/
 public class Calculator {
 
-    private String screen = "0";
+    private String screen = "";
 
     private double latestValue;
 
@@ -37,8 +37,11 @@ public void pressDotKey() {
         if(!screen.endsWith(".")) screen = screen + ".";
     }
 
-    public void pressNegative() {
-        screen = screen.startsWith("-") ? screen.substring(1) : "-" + screen;
+    public void pressNegative(){
+        if(!screen.startsWith("-")) screen = "-" + screen;
+        else {
+            if (!screen.endsWith("-")) screen = screen + "-";
+        }
     }
 
     public void pressEquals() {
@@ -47,6 +50,7 @@ public void pressEquals() {
             case "-" -> latestValue - Double.parseDouble(screen);
             case "x" -> latestValue * Double.parseDouble(screen);
             case "/" -> latestValue / Double.parseDouble(screen);
+            case "1/x" -> 1 / Double.parseDouble(screen);
             default -> throw new IllegalArgumentException();
         };
         screen = Double.toString(result);
diff --git a/src/test/java/tdd/setup/CalculatorTest.java b/src/test/java/tdd/setup/CalculatorTest.java
index 3bf16e9..e7062fd 100644
--- a/src/test/java/tdd/setup/CalculatorTest.java
+++ b/src/test/java/tdd/setup/CalculatorTest.java
@@ -16,4 +16,33 @@ void calculatorCanDoTwoPlusTwo() {
         calc.pressEquals();
         assertEquals("4", calc.readScreen());
     }
+    @Test
+    @DisplayName("should display clear result after divide two positive numbers")
+    void calculatorCanClearDisplay() {
+        Calculator calc = new Calculator();
+        calc.pressDigitKey(3);
+        calc.pressOperationKey("/");
+        calc.pressDigitKey(2);
+        calc.pressEquals();
+        calc.pressClearKey();
+        assertEquals("0", calc.readScreen());
+    }
+    @Test
+    @DisplayName("New Button for Fractional")
+    void calculatorFractional() {
+        Calculator calc = new Calculator();
+        calc.pressDigitKey(3);
+        calc.pressOperationKey("1/x");
+        calc.pressEquals();
+        assertEquals("0.3333333333333333", calc.readScreen());
+    }
+
+    @Test
+    @DisplayName("Processing negative numbers")
+    void calculatorNegativeNumbers() {
+        Calculator calc = new Calculator();
+        calc.pressDigitKey(9);
+        calc.pressNegative();
+        assertEquals("-9", calc.readScreen());
+    }
 }