Mathematics behind credit card Numbers

Credit card numbers use the Luhn algorithm. Digits are weighted, doubled, and summed so the final total ends in zero. One wrong digit usually breaks the math, letting systems catch typos instantly without storing the real number.

Yes it's a valid card number

Why when doubling 8 and 6 did it go to 17 and 13? Are they doubling and then adding the 1 infront to the 2nd number?

@grok is it true

Sound in the background is MONTAGEM COMA by Andromeda & elysian

🥱🥱

@DealsDhamaka

What if last digit is zero?

@StreamviDL download