diff --git a/xml/System.Numerics/INumberBase`1.xml b/xml/System.Numerics/INumberBase`1.xml
index ec76083e56f..35990eef2c4 100644
--- a/xml/System.Numerics/INumberBase`1.xml
+++ b/xml/System.Numerics/INumberBase`1.xml
@@ -782,6 +782,8 @@ A return value of `false` does not imply that <xref:System.Numerics.INumberBase%
 
 This function returns `true` for a complex number `a + bi` where `b` is zero.
 
+This function checks values against the extended real number line, thus returns `true` for positive and negative infinity.
+
           ]]></format>
         </remarks>
       </Docs>
diff --git a/xml/System.Runtime.InteropServices/NFloat.xml b/xml/System.Runtime.InteropServices/NFloat.xml
index adda2d7805e..f23f1721ab5 100644
--- a/xml/System.Runtime.InteropServices/NFloat.xml
+++ b/xml/System.Runtime.InteropServices/NFloat.xml
@@ -2414,6 +2414,8 @@ A return value of `false` does not imply that <xref:System.Numerics.INumberBase%
 
 This function returns `true` for a complex number `a + bi` where `b` is zero.
 
+This function checks values against the extended real number line, thus returns `true` for <xref:System.Runtime.InteropServices.NFloat.PositiveInfinity> and <xref:System.Runtime.InteropServices.NFloat.NegativeInfinity>.
+
           ]]></format>
         </remarks>
         <inheritdoc cref="M:System.Numerics.INumberBase`1.IsRealNumber(`0)" />
diff --git a/xml/System/Double.xml b/xml/System/Double.xml
index 4648e9456c0..fdb25300a76 100644
--- a/xml/System/Double.xml
+++ b/xml/System/Double.xml
@@ -3154,6 +3154,8 @@ A return value of `false` does not imply that <xref:System.Numerics.INumberBase%
 
 This function returns `true` for a complex number `a + bi` where `b` is zero.
 
+This function checks values against the extended real number line, thus returns `true` for <xref:System.Double.PositiveInfinity> and <xref:System.Double.NegativeInfinity>.
+
           ]]></format>
         </remarks>
         <inheritdoc cref="M:System.Numerics.INumberBase`1.IsRealNumber(`0)" />
diff --git a/xml/System/Half.xml b/xml/System/Half.xml
index 85e27961d12..0c8e47422b0 100644
--- a/xml/System/Half.xml
+++ b/xml/System/Half.xml
@@ -2360,6 +2360,8 @@ A return value of `false` does not imply that <xref:System.Numerics.INumberBase%
 
 This function returns `true` for a complex number `a + bi` where `b` is zero.
 
+This function checks values against the extended real number line, thus returns `true` for <xref:System.Half.PositiveInfinity> and <xref:System.Half.NegativeInfinity>.
+
           ]]></format>
         </remarks>
         <inheritdoc cref="M:System.Numerics.INumberBase`1.IsRealNumber(`0)" />
diff --git a/xml/System/Single.xml b/xml/System/Single.xml
index a724fd54153..46f5625efc2 100644
--- a/xml/System/Single.xml
+++ b/xml/System/Single.xml
@@ -3171,6 +3171,8 @@ A return value of `false` does not imply that <xref:System.Numerics.INumberBase%
 
 This function returns `true` for a complex number `a + bi` where `b` is zero.
 
+This function checks values against the extended real number line, thus returns `true` for <xref:System.Single.PositiveInfinity> and <xref:System.Single.NegativeInfinity>.
+
           ]]></format>
         </remarks>
         <inheritdoc cref="M:System.Numerics.INumberBase`1.IsRealNumber(`0)" />