Dividing by 7 is also a cool trick and it’s way easier than this. 1/7th is 0.142857 recurring. All you need to remember is one-four-two-eight-five-seven. Say i

Dividing by 7 is also a cool trick and it’s way easier than this. 1/7th is 0.142857 recurring. All you need to remember is one-four-two-eight-five-seven. Say it over and over. It’s my favourite number. The magic: to get 2/7, 3/7, any/7, just move the decimal point: - 2/7: 0.285714285714… - 3/7: 0.428571428571… - 4/7: 0.571428571428… (I’m typing these out but ‘from memory’ but not really: only by knowing 1-4-2-8-5-7) - 5/7 & 6/7: left as an exercise for the reader. So then the trick is to play a bit of mental magic. Pretend like this is really hard and that every decimal point is stretching your mental capacity to its very edge. 31/7? That’s 4, with 3/7 left over. Say it out loud as you gaze in to the middle distance and do this difficult, difficult calculation in your head: “four point four two eight five seven … one four … two eight five … seven one four …” and so on. A fun trick which is very occasionally practically useful.