I came across an interesting feature of factorials while making the puzzle books at https://www.kakurokokoro.com https://www.kakurokokoro.com The widest two ro

I came across an interesting feature of factorials while making the puzzle books at https://www.kakurokokoro.com https://www.kakurokokoro.com The widest two rows are nine digits across, but while the first can be any of arrangements of the digits 1-9, the second cannot repeat any digits in the same columns, and so it limits allowable permutations to the number of derangements — which is close to 9!/e (where e is Euler’s Constant 2.718…) No idea what this has to do with the relationship of i and pi.