New divisibility rule! (30,000 of them)

About

I do mathematics and stand-up. Sometimes simultaneously. Occasionally while being filmed. (It's quite the Venn diagram.) You can send business stuff to [email protected] and maths to [email protected] (but everything gets to me one way or another). I'm also in these places: http://standupmaths.com http://twitter.com/standupmaths https://m.bilibili.com/space/475271755