Reapply modulo helpers and inline fast remainders

PerfectNumbers.Core.Tests/UIntExtensionsTests.cs

@@ -27,6 +27,17 @@ public class UIntExtensionsTests
         value.Mod5().Should().Be(value % 5U);
     }
 
+    [Theory]
+    [Trait("Category", "Fast")]
+    [InlineData(0U)]
+    [InlineData(1U)]
+    [InlineData(1234567890U)]
+    [InlineData(uint.MaxValue)]
+    public void Mod6_matches_operator(uint value)
+    {
+        value.Mod6().Should().Be(value % 6U);
+    }
+
     [Theory]
     [Trait("Category", "Fast")]
     [InlineData(0U)]