Overview
In this challenge, you will be given a starter solution with a number of TODO comments that are designed to help you along the way. When you feel you have completed the challenge, you can submit your solution and have it automatically tested to ensure it behaves exactly as requested. Note, the automated tests are also looking out for the suggestions made in the additional challenges section at the end of this document. Consequently, you will need to ensure the messages returned from the ValidateNumber method and the data that gets written to the console match the specification. If you get really stuck, the full solution is located in the LuhnChallengeEnd folder