Sound, Radio & InformationError Detection
Your Card's Last Digit Is a Lie Detector
The final digit of a card number checks all the others
Type one wrong digit of your card number and many checkout forms object instantly, before any bank sees it. How can they tell?
You'll find out
- How a form spots a typo on its own
- The one swap that sneaks past
- Where else check digits guard you
Why it matters
Cards, barcodes and bank transfers lean on check digits to stop a slip of the finger from becoming a costly mistake.
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