why not to use just long? Don't see any need in BigInteger

Thanks

The Kata is absoluetely not ready:

1. You write, that first letter should be capitalized, but you don't write about other letters, they should be on lower case, independet of source.
2. The signature of the method in template is wrong: it is int should be string[]
3. No testcases templates. It's not ok, they are in the description, just fill template with [TestFixture]
   public class CapitaliseTest
   {
   [Test]
   public void Test1()
   {
   Assert.AreEqual(new[] { "Jo", "Nelson", "Jurie" }, Kata20.CapMe(new[] { "jo", "nelson", "jurie" }));
   }
   }

so for me this kata should go back to beta.

it's good now, thank you!

No predefined Class Kata, just the method, so is the code not compilebar

Do you really need to have return type Boolean? Why not simple bool ?

Please note, than a and b are not ordered, so could happen that a<b and that b<a