987654321 / 123456789(johndcook.com)
613 points by ColinWright | 100 comments
John D. Cook blog post examining why 987654321/123456789 is nearly 8 and whether analogous digit ratios in other bases are close to integers.
#recreational-math on Hacker News
3 stories tagged recreational-math, newest first.
6174(en.wikipedia.org)
443 points by gone35 | 90 comments
Wikipedia article on 6174, Kaprekar's constant, the fixed point reached by repeatedly subtracting ascending from descending digit arrangements of four-digit numbers.
37, the median value for the second prime factor of an integer(grossack.site)
416 points by sacrosanct | 185 comments
Blog post by Chris Grossack exploring the fact that 37 is the median value of the second smallest prime factor of an integer, verified with Sage.