There's a seemingly throwaway joke in the Marge in Chains episode of The Simpsons when Apu boasts about his memory by saying he can recite pi to 40,000 decimal places ("the last digit is 1"). It's a funny line even if it wasn't accurate, but according to author Simon Singh - who has written the book The Simpsons and Their Mathematical Secrets - it's an indicator of the show's twenty-five year obsession with numbers.

Seemingly, pi's 40,000th number is indeed 1, and The Simpsons writers actually consulted a pi expert to verify that fact. Said expert is the man behind a complex formula for determining any given decimal point of π.

It's not just a once-off case, although the depth, effort and thought process behind that quickfire gag is the subject of the video below where Singh explains some of The Simpsons' mathematical complexity. Not only that, the gag can also help prove that the show offers a consistent logic behind its internal number system.

Check out the Numberphile video below, which doubles as a fascinating, enjoyable maths lessons for a Friday afternoon: