diff --git a/src/StrategyPatternExample/IMathOperator.cs b/src/StrategyPatternExample/IMathOperator.cs
index 7451c71..251d356 100644
--- a/src/StrategyPatternExample/IMathOperator.cs
+++ b/src/StrategyPatternExample/IMathOperator.cs
@@ -2,7 +2,7 @@
 {
     public interface IMathOperator
     {
-        Operator Operator { get; }
+        bool IsApplicable(Operator op);
 
         int Calculate(int a, int b);
     }
diff --git a/src/StrategyPatternExample/MathStrategy.cs b/src/StrategyPatternExample/MathStrategy.cs
index ed864a9..f05f5f9 100644
--- a/src/StrategyPatternExample/MathStrategy.cs
+++ b/src/StrategyPatternExample/MathStrategy.cs
@@ -15,7 +15,15 @@ public MathStrategy(IEnumerable<IMathOperator> operators)
 
         public int Calculate(int a, int b, Operator op)
         {
-            return _operators.FirstOrDefault(x => x.Operator == op)?.Calculate(a, b) ?? throw new ArgumentNullException(nameof(op));
+            foreach (var @operator in _operators)
+            {
+                if (@operator.IsApplicable(op))
+                {
+                    return @operator.Calculate(a, b);
+                }
+            }
+
+            throw new ArgumentNullException(nameof(op));
         }
     }
 }
\ No newline at end of file
diff --git a/src/StrategyPatternExample/Operators/AddOperator.cs b/src/StrategyPatternExample/Operators/AddOperator.cs
index 1e127f1..8ce981f 100644
--- a/src/StrategyPatternExample/Operators/AddOperator.cs
+++ b/src/StrategyPatternExample/Operators/AddOperator.cs
@@ -2,7 +2,10 @@
 {
     public class AddOperator : IMathOperator
     {
-        public Operator Operator => Operator.Add;
+        public bool IsApplicable(Operator op)
+        {
+            return op == Operator.Add;
+        }
 
         public int Calculate(int a, int b) => a + b;
     }
diff --git a/src/StrategyPatternExample/Operators/DivideOperator.cs b/src/StrategyPatternExample/Operators/DivideOperator.cs
index c428301..b0d2305 100644
--- a/src/StrategyPatternExample/Operators/DivideOperator.cs
+++ b/src/StrategyPatternExample/Operators/DivideOperator.cs
@@ -4,7 +4,10 @@ namespace StrategyPatternExample
 {
     public class DivideOperator : IMathOperator
     {
-        public Operator Operator => Operator.Divide;
+        public bool IsApplicable(Operator op)
+        {
+            return op == Operator.Divide;
+        }
 
         public int Calculate(int a, int b)
         {
diff --git a/src/StrategyPatternExample/Operators/MultipleOperator.cs b/src/StrategyPatternExample/Operators/MultipleOperator.cs
index 5b075ce..2282c1d 100644
--- a/src/StrategyPatternExample/Operators/MultipleOperator.cs
+++ b/src/StrategyPatternExample/Operators/MultipleOperator.cs
@@ -2,7 +2,10 @@
 {
     public class MultipleOperator : IMathOperator
     {
-        public Operator Operator => Operator.Multiple;
+        public bool IsApplicable(Operator op)
+        {
+            return op == Operator.Multiple;
+        }
 
         public int Calculate(int a, int b) => a * b;
     }
diff --git a/src/StrategyPatternExample/Operators/SubtractOperator.cs b/src/StrategyPatternExample/Operators/SubtractOperator.cs
index dd5de7f..73dfe03 100644
--- a/src/StrategyPatternExample/Operators/SubtractOperator.cs
+++ b/src/StrategyPatternExample/Operators/SubtractOperator.cs
@@ -2,7 +2,10 @@
 {
     public class SubtractOperator : IMathOperator
     {
-        public Operator Operator => Operator.Substract;
+        public bool IsApplicable(Operator op)
+        {
+            return op == Operator.Substract;
+        }
 
         public int Calculate(int a, int b) => a - b;
     }
diff --git a/src/StrategyPatternExample/StrategyPatternExample.csproj b/src/StrategyPatternExample/StrategyPatternExample.csproj
index 965e3b7..4c4f12a 100644
--- a/src/StrategyPatternExample/StrategyPatternExample.csproj
+++ b/src/StrategyPatternExample/StrategyPatternExample.csproj
@@ -9,7 +9,7 @@
   </ItemGroup>
 
   <ItemGroup>
-    <PackageReference Include="Microsoft.AspNetCore.All" Version="2.0.5" />
+    <PackageReference Include="Microsoft.AspNetCore.All" Version="2.0.9" />
   </ItemGroup>
 
 </Project>