Last digit changes using data validation

Hello,
I have a form that contains credit card numbers. I have set up a validation block to hold those numbers, however, I’ve run into a problem with Excel simply changing the last digit. IE: 4000120078135436, becomes 4000120078135430. I’ve tried setting the validation up thusly:
Allow whole number >0
Allow whole number >9
Allow whole number between 0, 9999999999999999
Allow whole number between 0, 99999999999999999
Allow whole number between 0, 0000000000000000
Allow Any Value, with the cell formatted to Custom, 0000000000000000
Nothing is keeping the number the way it was originally typed. If I set the validation to text, it will alleviate the problem of the number being right, however it will defeat the purpose of creating a cell to hold only numbers.