diff --git a/source/Trek-12/ConsoleApp/Program.cs b/source/Trek-12/ConsoleApp/Program.cs
index 69dfa14..adc70f7 100644
--- a/source/Trek-12/ConsoleApp/Program.cs
+++ b/source/Trek-12/ConsoleApp/Program.cs
@@ -76,7 +76,7 @@ class Program
     static void OnDiceRolled(object sender, DiceRolledEventArgs e)
     {
         Console.WriteLine($"Dice 1: {e.Dice1Value} | Dice 2: {e.Dice2Value}");
-        Operation playerOperation = GetPlayerOperation();
+        Operation playerOperation = GetPlayerOperation(sender);
         ((Game)sender).HandlePlayerOperation(playerOperation);
     }
 
@@ -230,7 +230,7 @@ class Program
     /// </summary>
     /// <returns></returns>
     /// <exception cref="ArgumentOutOfRangeException"></exception>
-    static Operation GetPlayerOperation()
+    static Operation GetPlayerOperation(object? sender)
     {
         DisplayOperationOptions();
         string? op = Console.ReadLine();
@@ -239,6 +239,14 @@ class Program
             Console.WriteLine("Invalid operation. Please choose again.");
             op = Console.ReadLine();
         }
+        int test = Convert.ToInt32(op);
+        while(((Game)sender).UsedMap.CheckOperationPossible(test-1))
+        {
+            Console.WriteLine("Invalid operation. Please choose again.");
+            Console.WriteLine();
+            op = Console.ReadLine();
+            test = Convert.ToInt32(op);
+        }
 
         return op switch
         {
diff --git a/source/Trek-12/Models/Game/Game.cs b/source/Trek-12/Models/Game/Game.cs
index 586ce34..a9b9d10 100644
--- a/source/Trek-12/Models/Game/Game.cs
+++ b/source/Trek-12/Models/Game/Game.cs
@@ -94,7 +94,7 @@ namespace Models.Game
         /// If the operation is MULTIPLICATION, it returns the product of the values of the two dice.
         /// If the operation is not one of the operations, it throws an ArgumentOutOfRangeException.
         /// </returns>
-        private int ResultOperation(Operation o)
+        public int ResultOperation(Operation o)
         {
             int result = o switch
             {
diff --git a/source/Trek-12/Models/Game/Map.cs b/source/Trek-12/Models/Game/Map.cs
index 56dbb69..ccc327b 100644
--- a/source/Trek-12/Models/Game/Map.cs
+++ b/source/Trek-12/Models/Game/Map.cs
@@ -74,5 +74,10 @@
             }
             return operationGrid;
         }
+
+        public bool CheckOperationPossible(int x)
+        {
+            return OperationGrid[x * 4 + 3].IsChecked;
+        }
     }
 }
\ No newline at end of file
diff --git a/source/Trek-12/Models/Game/OperationCell.cs b/source/Trek-12/Models/Game/OperationCell.cs
index d8ac6da..4667ff0 100644
--- a/source/Trek-12/Models/Game/OperationCell.cs
+++ b/source/Trek-12/Models/Game/OperationCell.cs
@@ -17,6 +17,7 @@ namespace Models.Game
         /// <param name="y"></param>
         public OperationCell(int x, int y) : base(x, y)
         {
+            IsChecked = false;
         }
 
         /// <summary>