diff --git a/src/main/java/tdd/setup/Calculator.java b/src/main/java/tdd/setup/Calculator.java
index 171f6d6..249f64f 100644
--- a/src/main/java/tdd/setup/Calculator.java
+++ b/src/main/java/tdd/setup/Calculator.java
@@ -15,7 +15,7 @@ public String readScreen() {
     public void pressDigitKey(int digit) {
         if(digit > 9 || digit < 0) throw new IllegalArgumentException();
 
-        if(latestOperation.isEmpty()) {
+        if(latestOperation.isEmpty() || screen.substring(screen.length()-1).equals(".")) {
             screen = screen + digit;
         } else {
             latestValue = Double.parseDouble(screen);
@@ -30,6 +30,9 @@ public void pressClearKey() {
     }
 
     public void pressOperationKey(String operation)  {
+        if (!this.latestOperation.isEmpty()) {
+        	pressEquals() ;
+        }
         latestOperation = operation;
     }
 
diff --git a/src/test/java/tdd/setup/CalculatorRoundingTest.java b/src/test/java/tdd/setup/CalculatorRoundingTest.java
new file mode 100644
index 0000000..ca9ab09
--- /dev/null
+++ b/src/test/java/tdd/setup/CalculatorRoundingTest.java
@@ -0,0 +1,23 @@
+package tdd.setup;
+
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+import static org.junit.jupiter.api.Assertions.*;
+
+@DisplayName("Retro calculator")
+class CalculatorRoundingTest {
+    @Test
+    @DisplayName("should display a rounded number")
+    void calculatorCanDoTwoPlusTwo() {
+        Calculator calc = new Calculator();
+        calc.pressDigitKey(1);
+        calc.pressDotKey();
+          calc.pressDigitKey(5);
+        calc.pressOperationKey("+");
+       calc.pressDigitKey(1);
+        calc.pressDotKey();
+          calc.pressDigitKey(5);
+        calc.pressEquals();
+        assertEquals("3", calc.readScreen());
+    }
+}
diff --git a/src/test/java/tdd/setup/CalculatorTest2.java b/src/test/java/tdd/setup/CalculatorTest2.java
new file mode 100644
index 0000000..7097bc3
--- /dev/null
+++ b/src/test/java/tdd/setup/CalculatorTest2.java
@@ -0,0 +1,22 @@
+package tdd.setup;
+
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+import static org.junit.jupiter.api.Assertions.*;
+
+@DisplayName("Retro calculator2")
+class CalculatorTest2 {
+    @Test
+    @DisplayName("should display negative result after adding two numbers")
+    void calculatorCanDosixPlusTen() {
+        Calculator calc = new Calculator();
+        calc.pressDigitKey(6);
+        calc.pressOperationKey("-");
+        calc.pressDigitKey(9);
+        calc.pressEquals();
+        assertEquals("-3", calc.readScreen());
+
+
+
+    }
+}
diff --git a/src/test/java/tdd/setup/MultipleOperationTest.java b/src/test/java/tdd/setup/MultipleOperationTest.java
new file mode 100644
index 0000000..2fdd238
--- /dev/null
+++ b/src/test/java/tdd/setup/MultipleOperationTest.java
@@ -0,0 +1,21 @@
+package tdd.setup;
+
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+import static org.junit.jupiter.api.Assertions.*;
+
+@DisplayName("Retro calculator")
+class MultipleOperationTest {
+    @Test
+    @DisplayName("should display a result after multiple additions")
+    void calculatorCanDoMultipleAddition() {
+        Calculator calc = new Calculator();
+        calc.pressDigitKey(1);
+        calc.pressOperationKey("+");
+        calc.pressDigitKey(3);
+        calc.pressOperationKey("+");
+        calc.pressDigitKey(5);
+        calc.pressEquals();
+        assertEquals("9", calc.readScreen());
+    }
+}