51–55 of 55 posts
I remember discovering that pi x 10^7 is very close to the number of seconds in a year while at uni. One of my tutors was convinced this had to be more than coincidence, but I always figured it was just chance and a nice but sometimes useful shortcut...
so the Earth's orbital velocity is 10^-4 c
The second fact, pi^2 ~= g, is famous enough that it has a separate section in Wikipedia [1]. [1] https://en.wikipedia.org/wiki/Mathematical_coincidence#Gravi...
As discovered by Randall Munroe, a cubic mile is close to 4/3 π cubic kilometres (within 0.5%). This means that a sphere with radius n kilometres has almost exactly the same volume as a cube with side length n miles.
I was a little disappointed that the upper range of gravity on earth only goes to 9.8337. Just a little more and there would have been somewhere on earth that was an exact match. It would have been the ideal (if chilly) place to start a cult.
The initial definition of the meter would have been such that g=pi^2. It was then adjusted but enough for it to remain an interesting (if not too good) approximation.
Quite a lot.
As an ex-physicist, pi^2 is 10. Like g. I get it that this is a nice calculation with the Zeta function and everything, but 3 and a small something squared will be near 10 so it is 10.
987654321 / 123456789 = 8 (to the 7th decimal place) is another nice one
I just wrote an article on that (and the fact that this submission on HN exists, I was not expecting that)