Here's my credit card number

Slight correction that doesn't affect 16-digit numbers but does affect 15-digit numbers (ex: amex): We would read right to left and double the even placements.

Brilliant! It all makes so much sense now

What the???

You're pretty cool dude. I like your math work.

This is awesome @howie_hua !!

That’s really cool, I never knew that about credit cards.

Hummmm.....,👌

My credit card digits add up to a pre number 🤷‍♂️

Thank you.