Code was added to ValidCheckSum member function. This will calculate the checksum of the account number and return true if it is equal to 0, or False if it is not 0. The previous test now passes
Added a test case to see if the previous code added can determine if a checksum is invalid. Test passes
Added a test case to try and validate a check sum of an account with illegible digits. This test failed since the program can't convert '?' to an integer during the check sum calculation.
Small snippet of code was added to teh ValidCheckSum meber function to return false if the number is illegible. All tests now pass.
Added documentation for ValidCheckSum member function