How can I find my credit card's security number?
Visa, MasterCard, Discover:
The three-digit (3) card security number is a printed number located on the back of the card, typically near the far right side. This number is usually separated from other sets of numbers on the card, and is the farthest towards the right.
The four-digit (4) card security number is a printed number located on the front of the card, above and to the right of the raised account number.