987654321 / 123456789

Post by iso1631 » Thu, Oct 30, 2025, 1:36 PM UTC

oersted wrote: post #8

alyxya wrote: post #4

I like to think of 0.987654... and 0.123456... as infinite series which simplify to 80/81 and 10/81, hence the ~8 ratio.

I didn't get where this comes from until I saw the second answer from the StackOverflow question another commenter shared. https://math.stackexchange.com/a/2268896 Apparently 1/9^2 is well known to be 0.12345679(012345679)... EDIT: Yes it's missing the 8 (I wrote it wrong intially): https://math.stackexchange.com/questions/994203/why-do-we-mi... Interesting how it works out but I don't think it is anywhere close to a…

Post by alyxya » Thu, Oct 30, 2025, 1:39 PM UTC

oersted wrote: post #8

alyxya wrote: post #4

I like to think of 0.987654... and 0.123456... as infinite series which simplify to 80/81 and 10/81, hence the ~8 ratio.

I didn't get where this comes from until I saw the second answer from the StackOverflow question another commenter shared. https://math.stackexchange.com/a/2268896 Apparently 1/9^2 is well known to be 0.12345679(012345679)... EDIT: Yes it's missing the 8 (I wrote it wrong intially): https://math.stackexchange.com/questions/994203/why-do-we-mi... Interesting how it works out but I don't think it is anywhere close to a…

Post by Joker_vD » Thu, Oct 30, 2025, 1:51 PM UTC

Post by tempfile » Thu, Oct 30, 2025, 1:55 PM UTC

madcaptenor wrote: post #7

MontyCarloHall wrote: post #3

In a similar vein, e^pi - pi = 19.9990999792, as referenced in this XKCD: https://xkcd.com/217/

Not really in a similar vein, because there's actually a good reason for this to be very close to an integer whereas there is no such reason for e^pi - pi.

Post by zkmon » Thu, Oct 30, 2025, 1:59 PM UTC

madcaptenor wrote: post #12

iso1631 wrote: post #11

Earlier quoted context omitted.

9^2 is 81 1/81 is 0.012345679012345679.... no 8 in sight

The 8 is there but then it's followed by a 9 and a 10, and the carry from the 10 ends up bumping it up.