Mathematical Coincidence

https://en.wikipedia.org/wiki/Mathematical_coincidence

by poletopole • 5 years ago

12 8 5 years ago

en.wikipedia.org

tromp• 5 years ago

The good approximation for pi is easier to remember as 1/pi ~ 113/355,

featuring doubled digits 11 33 55.

ksd482• 5 years ago

22/7 as well

wastholm• 5 years ago

I don't know if it qualifies as a "mathematical coincidence" or not, but I find it amusing to demonstrate to kids that you can multiply 142,857 by 1, 2, 3, etc., and the result is always a number with the same digits but in a different order:

2 × 142,857 = 285,714

3 × 142,587 = 428,571

4 × 142,587 = 571,428

Etc. But then, suddenly:

7 × 142,857 = 999,999

carrolldunham• 5 years ago

Some kids might love that but I wonder if it's also the kind of thing that makes many kids resent math and ask why do we have to learn this. Since its just like nerd party trick that reveals nothing about the world and in fact makes the world especially math, seem even more impenetrable.

captn3m0• 5 years ago

There's actually some interesting math behind it: https://en.wikipedia.org/wiki/Cyclic_number, https://www.youtube.com/watch?v=WUlaUalgxqI (Numberphile)

xtiansimon• 5 years ago

You’re not wrong. The difference (and this does not apply here in an open forum) must be the quality of teaching. Strange math tricks by themselves are empty calories.

progre• 5 years ago

Hey, XKCD-guy gets a mention!

riskneutral• 5 years ago

Wouldn't this be more properly categorized as a numerical approximation?

Mathematical Coincidence

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