Factor out DigitsTable
Unneeded
Added second constructor with a string argument
Added Unit Test for AccountNumber
Refactor ParseDigits into a separate class
Added AccountNumber Unit Test
New constructor added to AccountNumber
Test AccountNumbers in sample file
Use ToString() instead of GetNumber() (which should return an integer by the way). Delete GetDigitByIndex() which isn't needed anymore.
Return a number instead of a string
Use TryGet... pattern
Remove old Checksum check
Remove obsolete constructor and changed code to read the sample file.
Copy sample file to output directory
Return illegible result and remove unnused code.