Download the Credit Card Library from Lucas Carlson.
sudo gem install creditcard
# Checksum Digit, there is an algorithm that checksum must match
# A. Import the libraries
# B. Boolean test as to whether this number is a valid credit card
puts '5276 4400 6542 1319'.creditcard?
# C. Check the type of credit card it is
puts '5276 4400 6542 1319'.creditcard_type