diff --git a/Test/Aufgabe2_KellerautomatTest.java b/Test/Aufgabe2_KellerautomatTest.java
index 961bdff..7bd0679 100644
--- a/Test/Aufgabe2_KellerautomatTest.java
+++ b/Test/Aufgabe2_KellerautomatTest.java
@@ -6,9 +6,9 @@ class Aufgabe2_KellerautomatTest {
 
     @Test
     void calculate() {
-        assertEquals('Z', Aufgabe2_Kellerautomat.calculate("ZZ+ZZ+ZZ+ZZ+***"));
-        assertEquals('Z', Aufgabe2_Kellerautomat.calculate("ZZ+ZZ+ZZZ+ZZZZ++Z++++++"));
-        assertEquals('$', Aufgabe2_Kellerautomat.calculate("ZZ+*"));
-        assertEquals('$', Aufgabe2_Kellerautomat.calculate("Z+Z+Z*Z*"));
+        assertEquals(6664, Aufgabe2_Kellerautomat.calculate("34+62+89+43+***"));
+        assertEquals(58, Aufgabe2_Kellerautomat.calculate("31+78+987+1214++7++++++"));
+        assertEquals(-1, Aufgabe2_Kellerautomat.calculate("34+*"));
+        assertEquals(-1, Aufgabe2_Kellerautomat.calculate("8+9+7*2*"));
     }
 }
\ No newline at end of file
diff --git a/src/Aufgabe2_Kellerautomat.java b/src/Aufgabe2_Kellerautomat.java
index f0a015f..a813e24 100644
--- a/src/Aufgabe2_Kellerautomat.java
+++ b/src/Aufgabe2_Kellerautomat.java
@@ -12,131 +12,138 @@ public class Aufgabe2_Kellerautomat {
         }
     }
 
-    public static char calculate(String word) {
+    public static int calculate(String word) {
         List<Character> wordChars = new ArrayList<>();
         for (char symbol : word.toCharArray()) {
             wordChars.add(symbol);
         }
-        ArrayList<Character> stack = new ArrayList<>();
-        stack.add('$');
+        ArrayList<Integer> stack = new ArrayList<>();
+        stack.add(-1);
 
         int state = 0; //case 0 - 5 = q0 - q5, case -1 = Abfallzustand
         char operator = '$';
-        char firstNumber = '$';
-        char secondNumber = '$';
-        char result = '$';
+        int firstNumber = 0;
+        int secondNumber = 0;
+        int result = -1;
 
         while (wordChars.size() > 0 || state >= 3) {
             char symbol;
-            Character stackSymbol = stack.remove(stack.size() - 1);
+            int stackSymbol = stack.remove(stack.size() - 1);
             switch (state) {
                 case 0:
-                    if (wordChars.remove(0) == 'Z' && stackSymbol == '$') {
-                        stack.add('$');
-                        stack.add('Z');
+                    symbol = wordChars.remove(0);
+                    if (!isOperator(symbol) && stackSymbol == -1) {
+                        stack.add(-1);
+                        stack.add(Character.getNumericValue(symbol));
                         state = 1;
                     } else {
                         dontAccept(word);
-                        return '$';
+                        return -1;
                     }
                     break;
                 case 1:
-                    if (wordChars.remove(0) == 'Z' && stackSymbol == 'Z') {
-                        stack.add('Z');
-                        stack.add('Z');
+                    symbol = wordChars.remove(0);
+                    if (!isOperator(symbol) && stackSymbol > -1) {
+                        stack.add(stackSymbol);
+                        stack.add(Character.getNumericValue(symbol));
                         state = 2;
                     } else {
                         dontAccept(word);
-                        return '$';
+                        return -1;
                     }
                     break;
                 case 2:
                     symbol = wordChars.remove(0);
-                    if (isOperator(symbol) && stackSymbol == 'Z') {
+                    if (isOperator(symbol) && stackSymbol > -1) {
                         operator = symbol;
                         firstNumber = stackSymbol;
                         state = 3;
-                    } else if (symbol == 'Z' && stackSymbol == 'Z') {
-                        stack.add('Z');
-                        stack.add('Z');
+                    } else if (!isOperator(symbol) && stackSymbol > -1) {
+                        stack.add(stackSymbol);
+                        stack.add(Character.getNumericValue(symbol));
                         state = 2;
-                    } else if (symbol == 'Z' && stackSymbol == '$') {
-                        stack.add('$');
-                        stack.add('Z');
+                    } else if (!isOperator(symbol) && stackSymbol == -1) {
+                        stack.add(-1);
+                        stack.add(Character.getNumericValue(symbol));
                         state = 2;
                     } else {
                         dontAccept(word);
-                        return '$';
+                        return -1;
                     }
                     break;
                 case 3:
-                    if (stackSymbol == 'Z') {
+                    if (stackSymbol > -1) {
                         secondNumber = stackSymbol;
                         stack.add(doOperation(operator, firstNumber, secondNumber));
                         state = 4;
                     } else {
                         dontAccept(word);
-                        return '$';
+                        return -1;
                     }
                     break;
                 case 4:
                     if (wordChars.size() > 0) {
                         symbol = wordChars.remove(0);
-                        if (symbol == 'Z' && stackSymbol == 'Z') {
-                            stack.add('Z');
-                            stack.add('Z');
+                        if (!isOperator(symbol) && stackSymbol > -1) {
+                            stack.add(stackSymbol);
+                            stack.add(Character.getNumericValue(symbol));
                             state = 2;
-                        } else if (isOperator(symbol) && stackSymbol == 'Z') {
+                        } else if (isOperator(symbol) && stackSymbol > -1) {
                             operator = symbol;
                             firstNumber = stackSymbol;
                             state = 3;
                         } else {
                             dontAccept(word);
-                            return '$';
+                            return -1;
                         }
                     } else {
-                        if (stackSymbol == 'Z') {
+                        if (stackSymbol > -1) {
                             result = stackSymbol;
                             state = 5;
                         } else {
                             dontAccept(word);
-                            return '$';
+                            return -1;
                         }
                     }
                     break;
                 case 5:
-                    if (stackSymbol == '$') {
-                        stack.add('$');
+                    if (stackSymbol == -1) {
+                        stack.add(-1);
                         state = 6;
                     } else {
                         dontAccept(word);
-                        return '$';
+                        return -1;
                     }
                     break;
                 case 6:
-                    accept(word);
+                    accept(word, result);
                     return result;
 
             }
         }
         dontAccept(word);
-        return '$';
+        return -1;
     }
 
     private static void dontAccept(String word) {
         System.out.println("Word: " + word  + "\nnot accepted");
     }
 
-    private static void accept(String word) {
-        System.out.println("Word: " + word  + "\naccepted ");
+    private static void accept(String word, int result) {
+        System.out.println("Word: " + word  + "\naccepted\nResult " + result);
     }
 
     private static boolean isOperator(char symbol){
         return symbol == '+' || symbol == '*';
     }
 
-    private static char doOperation(char doOperation, char firstNumber, char secondNumber){
-        return 'Z';
+    private static int doOperation(char operator, int firstNumber, int secondNumber){
+        if(operator == '+'){
+            return firstNumber + secondNumber;
+        } else if(operator == '*'){
+            return firstNumber * secondNumber;
+        }
+        return -1;
     }
 
 }