Luhn Checksum
The mod-10 check behind card numbers and IMEIs, demoing the p/moul/x/daily/luhn library.
Append a number to the path to check it — spaces and hyphens are ignored.
Samples
| number | valid? | note |
|---|---|---|
79927398713 |
✅ valid | the textbook example |
79927398710 |
❌ invalid | same number, wrong check digit |
4539148803436467 |
✅ valid | a test card number |
4539148803436647 |
❌ invalid | same card, two digits swapped |
Luhn is a typo check, not a security check: it catches every single-digit error and nearly every swap of adjacent digits, but anyone can compute a valid number. Never authorize anything with it.
