Header Banner
WonderHowTo Logo
WonderHowTo
Cons
wonderhowto.mark.png
Gadget Hacks Next Reality Food Hacks Null Byte The Secret Yumiverse Invisiverse Macgyverisms Mind Hacks Mad Science Lock Picking Driverless
Home
Cons

How to Tell Whether a Credit Card Number Is Valid Just by Looking at It

Think credit card numbers are just a meaningless jumble of digits? A sort of number soup? Think again! Your credit card number isn't even number at all but rather a composite of four separate numbers, each of which plays an important, fixed role.

Credit cards featuring Visa and MasterCard logos.

Because of these roles, you can figure out a lot about a card just by looking at its number. With a little bit of back-of-the-napkin math, you can, in fact, even determine whether a given credit card number is valid or not—which, if nothing else, is a great party trick.

Interested in cracking the credit card code for yourself? Here's how it works:

Tips

  • Having trouble validating your card? A Mint.com forum user writes, "Some cards use a variation – 'Mod 10 plus 5', so they accept as valid if the sum ends with 0 or 5."

Want more? Explore WonderHowTo's collection of credit card videos.

Apple's iOS 26 and iPadOS 26 updates are packed with new features, and you can try them before almost everyone else. First, check Gadget Hacks' list of supported iPhone and iPad models, then follow the step-by-step guide to install the iOS/iPadOS 26 beta — no paid developer account required.

Related Articles

Comments

No Comments Exist

Be the first, drop a comment!