diff --git a/source/Trek-12/Models/Rules/Rules.cs b/source/Trek-12/Models/Rules/Rules.cs
index 73d4467..95859d7 100644
--- a/source/Trek-12/Models/Rules/Rules.cs
+++ b/source/Trek-12/Models/Rules/Rules.cs
@@ -197,7 +197,7 @@ namespace Models.Rules
                 calculus += zones[i].Count - 1 + zones[i][0].Value;
                 if (zones[i].Count > 9)
                 {
-                    calculus += (zones[i].Count - 9) * 5;
+                    calculus += (zones[i].Count - 9) * 5 - (zones[i].Count - 9);
                 }
             }
             return calculus;
diff --git a/source/Trek-12/Tests/RulesTests.cs b/source/Trek-12/Tests/RulesTests.cs
index 630cca2..7cfe05a 100644
--- a/source/Trek-12/Tests/RulesTests.cs
+++ b/source/Trek-12/Tests/RulesTests.cs
@@ -462,17 +462,64 @@ public class RulesTests
         Assert.Equal(0, rules.FinalCalculusOfZones(new List<List<Cell>>()));
     }
 
-    /*
     [Fact]
     public void FinalCalculusOfZones_ReturnsCorrectValue_WhenZonesAreNotEmpty()
     {
-        // TODO
+        Rules rules = new Rules();
+        Cell cell = new Cell(0, 0);
+        cell.Value = 1;
+        Cell cell1 = new Cell(0, 1);
+        cell1.Value = 1;
+        Cell cell2 = new Cell(0, 2);
+        cell2.Value = 1;
+        Cell uncell = new Cell(0, 0);
+        uncell.Value = 4;
+        Cell deuxcell = new Cell(0, 1);
+        deuxcell.Value = 4;
+        Cell troiscell = new Cell(0, 2);
+        troiscell.Value = 4;
+        List<List<Cell>> zones = new List<List<Cell>>
+        {
+            new List<Cell> { cell, cell1, cell2 },
+            new List<Cell> { uncell, deuxcell, troiscell }
+        };
+
+        Assert.Equal(9, rules.FinalCalculusOfZones(zones));
     }
     
     [Fact]
     public void FinalCalculusOfZones_ReturnsCorrectValue_WhenZoneCountIsGreaterThanNine()
     {
-        // TODO
+        Rules rules = new Rules();
+        Cell cell = new Cell(0, 0);
+        cell.Value = 5;
+        Cell cell1 = new Cell(0, 1);
+        cell1.Value = 5;
+        Cell cell2 = new Cell(0, 2);
+        cell2.Value = 5;
+        Cell cell3 = new Cell(0, 3);
+        cell3.Value = 5;
+        Cell cell4 = new Cell(0, 4);
+        cell4.Value = 5;
+        Cell cell5 = new Cell(0, 5);
+        cell5.Value = 5;
+        Cell cell6 = new Cell(1, 0);
+        cell6.Value = 5;
+        Cell cell7 = new Cell(1, 1);
+        cell7.Value = 5;
+        Cell cell8 = new Cell(1, 2);
+        cell8.Value = 5;
+        Cell cell9 = new Cell(1, 3);
+        cell9.Value = 5;
+        Cell cell10 = new Cell(1, 4);
+        cell10.Value = 5;
+
+        List<List<Cell>> zones = new List<List<Cell>>
+        {
+            new List<Cell> { cell, cell1, cell2, cell3, cell4, cell5, cell6, cell7, cell8, cell9, cell10 }
+        };
+
+        Assert.Equal(23, rules.FinalCalculusOfZones(zones));
     }
-    */
+    
 }
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