Index: Ringtoets/MacroStabilityInwards/src/Ringtoets.MacroStabilityInwards.Forms/Properties/Resources.Designer.cs
===================================================================
diff -u -rc6719f7c61c39cbeda54d041a604c98cc4a83970 -re0797d05e1922d42790cc9f5eb41b923c23f763c
--- Ringtoets/MacroStabilityInwards/src/Ringtoets.MacroStabilityInwards.Forms/Properties/Resources.Designer.cs	(.../Resources.Designer.cs)	(revision c6719f7c61c39cbeda54d041a604c98cc4a83970)
+++ Ringtoets/MacroStabilityInwards/src/Ringtoets.MacroStabilityInwards.Forms/Properties/Resources.Designer.cs	(.../Resources.Designer.cs)	(revision e0797d05e1922d42790cc9f5eb41b923c23f763c)
@@ -1191,6 +1191,24 @@
         }
         
         /// <summary>
+        ///   Looks up a localized string similar to Het aantal tangentlijnen dat bepaald moet worden..
+        /// </summary>
+        public static string TangentLineNumber_Description {
+            get {
+                return ResourceManager.GetString("TangentLineNumber_Description", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Aantal tangentlijnen.
+        /// </summary>
+        public static string TangentLineNumber_DisplayName {
+            get {
+                return ResourceManager.GetString("TangentLineNumber_DisplayName", resourceCulture);
+            }
+        }
+        
+        /// <summary>
         ///   Looks up a localized string similar to Verticale coördinaat van de onderste raaklijn..
         /// </summary>
         public static string TangentLineZBottom_Description {
Index: Ringtoets/MacroStabilityInwards/src/Ringtoets.MacroStabilityInwards.Forms/Properties/Resources.resx
===================================================================
diff -u -rc6719f7c61c39cbeda54d041a604c98cc4a83970 -re0797d05e1922d42790cc9f5eb41b923c23f763c
--- Ringtoets/MacroStabilityInwards/src/Ringtoets.MacroStabilityInwards.Forms/Properties/Resources.resx	(.../Resources.resx)	(revision c6719f7c61c39cbeda54d041a604c98cc4a83970)
+++ Ringtoets/MacroStabilityInwards/src/Ringtoets.MacroStabilityInwards.Forms/Properties/Resources.resx	(.../Resources.resx)	(revision e0797d05e1922d42790cc9f5eb41b923c23f763c)
@@ -466,6 +466,12 @@
   <data name="TangentLineZTop_DisplayName" xml:space="preserve">
     <value>Tangentlijn Z-boven [m+NAP]</value>
   </data>
+  <data name="TangentLineNumber_Description" xml:space="preserve">
+    <value>Het aantal tangentlijnen dat bepaald moet worden.</value>
+  </data>
+  <data name="TangentLineNumber_DisplayName" xml:space="preserve">
+    <value>Aantal tangentlijnen</value>
+  </data>
   <data name="XLeft_Description" xml:space="preserve">
     <value>Horizontale coördinaat van de linker kant van het rekengrid.</value>
   </data>
Index: Ringtoets/MacroStabilityInwards/src/Ringtoets.MacroStabilityInwards.Forms/PropertyClasses/MacroStabilityInwardsGridSettingsProperties.cs
===================================================================
diff -u -r80453e2dd117acdee9dd3f57a4374516b828c1ea -re0797d05e1922d42790cc9f5eb41b923c23f763c
--- Ringtoets/MacroStabilityInwards/src/Ringtoets.MacroStabilityInwards.Forms/PropertyClasses/MacroStabilityInwardsGridSettingsProperties.cs	(.../MacroStabilityInwardsGridSettingsProperties.cs)	(revision 80453e2dd117acdee9dd3f57a4374516b828c1ea)
+++ Ringtoets/MacroStabilityInwards/src/Ringtoets.MacroStabilityInwards.Forms/PropertyClasses/MacroStabilityInwardsGridSettingsProperties.cs	(.../MacroStabilityInwardsGridSettingsProperties.cs)	(revision e0797d05e1922d42790cc9f5eb41b923c23f763c)
@@ -44,8 +44,9 @@
         private const int tangentLineDeterminationTypePropertyIndex = 3;
         private const int tangentLineZTopPropertyIndex = 4;
         private const int tangentLineZBottomPropertyIndex = 5;
-        private const int leftGridPropertyIndex = 6;
-        private const int rightGridPropertyIndex = 7;
+        private const int tangentLineNumberPropertyIndex = 6;
+        private const int leftGridPropertyIndex = 7;
+        private const int rightGridPropertyIndex = 8;
 
         private readonly IObservablePropertyChangeHandler propertyChangeHandler;
 
@@ -154,6 +155,23 @@
             }
         }
 
+        [PropertyOrder(tangentLineNumberPropertyIndex)]
+        [DynamicReadOnly]
+        [ResourcesCategory(typeof(Resources), nameof(Resources.GridSettings_DisplayName))]
+        [ResourcesDisplayName(typeof(Resources), nameof(Resources.TangentLineNumber_DisplayName))]
+        [ResourcesDescription(typeof(Resources), nameof(Resources.TangentLineNumber_Description))]
+        public int TangentLineNumber
+        {
+            get
+            {
+                return data.TangentLineNumber;
+            }
+            set
+            {
+                PropertyChangeHelper.ChangePropertyAndNotify(() => data.TangentLineNumber = value, propertyChangeHandler);
+            }
+        }
+
         [PropertyOrder(leftGridPropertyIndex)]
         [ResourcesCategory(typeof(Resources), nameof(Resources.GridSettings_DisplayName))]
         [ResourcesDisplayName(typeof(Resources), nameof(Resources.LeftGrid_DisplayName))]
@@ -183,7 +201,7 @@
         [DynamicReadOnlyValidationMethod]
         public bool DynamicReadOnlyValidationMethod(string propertyName)
         {
-            if (propertyName == nameof(TangentLineZTop) || propertyName == nameof(TangentLineZBottom))
+            if (propertyName == nameof(TangentLineZTop) || propertyName == nameof(TangentLineZBottom) || propertyName == nameof(TangentLineNumber))
             {
                 return data.TangentLineDeterminationType == MacroStabilityInwardsTangentLineDeterminationType.LayerSeparated
                        || AreGridSettingsReadOnly();
Index: Ringtoets/MacroStabilityInwards/test/Ringtoets.MacroStabilityInwards.Forms.Test/PropertyClasses/MacroStabilityInwardsGridSettingsPropertiesTest.cs
===================================================================
diff -u -r55f1926dba5945d7b2ef8adabb2ba3c8ad6c21ce -re0797d05e1922d42790cc9f5eb41b923c23f763c
--- Ringtoets/MacroStabilityInwards/test/Ringtoets.MacroStabilityInwards.Forms.Test/PropertyClasses/MacroStabilityInwardsGridSettingsPropertiesTest.cs	(.../MacroStabilityInwardsGridSettingsPropertiesTest.cs)	(revision 55f1926dba5945d7b2ef8adabb2ba3c8ad6c21ce)
+++ Ringtoets/MacroStabilityInwards/test/Ringtoets.MacroStabilityInwards.Forms.Test/PropertyClasses/MacroStabilityInwardsGridSettingsPropertiesTest.cs	(.../MacroStabilityInwardsGridSettingsPropertiesTest.cs)	(revision e0797d05e1922d42790cc9f5eb41b923c23f763c)
@@ -45,8 +45,9 @@
         private const int expectedTangentLineDeterminationTypePropertyIndex = 2;
         private const int expectedTangentLineZTopPropertyIndex = 3;
         private const int expectedTangentLineZBottomPropertyIndex = 4;
-        private const int expectedLeftGridPropertyIndex = 5;
-        private const int expectedRightGridPropertyIndex = 6;
+        private const int expectedTangentLineNumberPropertyIndex = 5;
+        private const int expectedLeftGridPropertyIndex = 6;
+        private const int expectedRightGridPropertyIndex = 7;
 
         [Test]
         public void Constructor_ExpectedValues()
@@ -112,7 +113,7 @@
             // Assert
             PropertyDescriptorCollection dynamicProperties = PropertiesTestHelper.GetAllVisiblePropertyDescriptors(properties);
 
-            Assert.AreEqual(7, dynamicProperties.Count);
+            Assert.AreEqual(8, dynamicProperties.Count);
 
             const string calculationGridsCategory = "Rekengrids";
 
@@ -156,6 +157,14 @@
                 "Verticale coördinaat van de onderste raaklijn.",
                 true);
 
+            PropertyDescriptor tangentLineNumberProperty = dynamicProperties[expectedTangentLineNumberPropertyIndex];
+            PropertiesTestHelper.AssertRequiredPropertyDescriptorProperties(
+                tangentLineNumberProperty,
+                calculationGridsCategory,
+                "Aantal tangentlijnen",
+                "Het aantal tangentlijnen dat bepaald moet worden.",
+                true);
+
             PropertyDescriptor leftGridProperty = dynamicProperties[expectedLeftGridPropertyIndex];
             TestHelper.AssertTypeConverter<MacroStabilityInwardsGridSettingsProperties, ExpandableObjectConverter>(nameof(properties.LeftGrid));
             PropertiesTestHelper.AssertRequiredPropertyDescriptorProperties(
@@ -202,6 +211,7 @@
             Assert.AreEqual(input.TangentLineDeterminationType, properties.TangentLineDeterminationType);
             Assert.AreEqual(input.TangentLineZTop, properties.TangentLineZTop);
             Assert.AreEqual(input.TangentLineZBottom, properties.TangentLineZBottom);
+            Assert.AreEqual(input.TangentLineNumber, properties.TangentLineNumber);
 
             bool gridIsReadOnly = gridDeterminationType == MacroStabilityInwardsGridDeterminationType.Automatic;
             Assert.AreSame(input.LeftGrid, properties.LeftGrid.Data);
@@ -225,22 +235,25 @@
             bool moveGrid = random.NextBoolean();
             var gridDeterminationType = random.NextEnumValue<MacroStabilityInwardsGridDeterminationType>();
             var tangentLineDeterminationType = random.NextEnumValue<MacroStabilityInwardsTangentLineDeterminationType>();
-            double tangentLineZTop = random.Next();
-            double tangentLineZBottom = random.Next();
+            double tangentLineZTop = random.NextDouble();
+            double tangentLineZBottom = random.NextDouble();
+            int tangentLineNumber = random.Next(1, 51);
 
             // When
             properties.MoveGrid = moveGrid;
             properties.GridDeterminationType = gridDeterminationType;
             properties.TangentLineDeterminationType = tangentLineDeterminationType;
             properties.TangentLineZTop = (RoundedDouble) tangentLineZTop;
             properties.TangentLineZBottom = (RoundedDouble) tangentLineZBottom;
+            properties.TangentLineNumber = tangentLineNumber;
 
             // Then
             Assert.AreEqual(moveGrid, input.MoveGrid);
             Assert.AreEqual(gridDeterminationType, input.GridDeterminationType);
             Assert.AreEqual(tangentLineDeterminationType, input.TangentLineDeterminationType);
             Assert.AreEqual(tangentLineZTop, input.TangentLineZTop, input.TangentLineZTop.GetAccuracy());
             Assert.AreEqual(tangentLineZBottom, input.TangentLineZBottom, input.TangentLineZBottom.GetAccuracy());
+            Assert.AreEqual(tangentLineNumber, input.TangentLineNumber);
         }
 
         [Test]
@@ -294,6 +307,16 @@
         }
 
         [Test]
+        public void TangentLineNumber_SetValidValue_SetsValueAndUpdatesObservers()
+        {
+            // Setup
+            var calculation = new MacroStabilityInwardsCalculationScenario();
+
+            // Call & Assert
+            SetPropertyAndVerifyNotifcationsForCalculation(properties => properties.TangentLineNumber = 10, calculation);
+        }
+
+        [Test]
         public void ToString_Always_ReturnEmptyString()
         {
             // Setup
@@ -324,8 +347,8 @@
             var input = new MacroStabilityInwardsInput
             {
                 GridDeterminationType = isGridDeterminationTypeAutomatic
-                                        ? MacroStabilityInwardsGridDeterminationType.Automatic
-                                        : MacroStabilityInwardsGridDeterminationType.Manual
+                                            ? MacroStabilityInwardsGridDeterminationType.Automatic
+                                            : MacroStabilityInwardsGridDeterminationType.Manual
             };
 
             var properties = new MacroStabilityInwardsGridSettingsProperties(input, changeHandler);
@@ -343,7 +366,8 @@
             [Values(true, false)] bool isTangentlineDeterminationTypeLayerSeparated,
             [Values(true, false)] bool isGridDeterminationTypeAutomatic,
             [Values(nameof(MacroStabilityInwardsGridSettingsProperties.TangentLineZTop),
-                nameof(MacroStabilityInwardsGridSettingsProperties.TangentLineZBottom))] string propertyName)
+                nameof(MacroStabilityInwardsGridSettingsProperties.TangentLineZBottom),
+                nameof(MacroStabilityInwardsGridSettingsProperties.TangentLineNumber))] string propertyName)
         {
             // Setup
             var mocks = new MockRepository();