public void GreatestCommonDivisor()
 {
     Assert.AreEqual(NumericUtilities.GreatestCommonDivisor(2, 3), 1);
     Assert.AreEqual(NumericUtilities.GreatestCommonDivisor(12, 8), 4);
     Assert.AreEqual(NumericUtilities.GreatestCommonDivisor(165, 15), 15);
     Assert.AreEqual(NumericUtilities.GreatestCommonDivisor(-8, 44), 4);
     Assert.AreEqual(NumericUtilities.GreatestCommonDivisor(41, 43), 1);
 }