I test numbers for divisibility by 7 in my head almost every time I do a daily KenKen puzzle. There's usually a four or five-digit number in there whose factors

I test numbers for divisibility by 7 in my head almost every time I do a daily KenKen puzzle. There's usually a four or five-digit number in there whose factors I don't know off the top of my head, so I'll give it a quick check for sevens just to get my bearings. But a python notebook could definitely beat me in a race.