This article says that NASA uses 15 digits after the decimal point, which I’m counting as 16 in total, since that’s how we count significant digits in scientific notation. If you round pi to 3, that’s one significant digit, and if you round it to 1, that’s zero digits.

I know that 22/7 is an extremely good approximation for pi, since it’s written with 3 digits, but is accurate to almost 4 digits. Another good one is √10, which is accurate to a little over 2 digits.

I’ve heard that ‘field engineers’ used to use these approximations to save time when doing math by hand. But what field, exactly? Can anyone give examples of fields that use fewer than 16 digits? In the spirit of something like xkcd: Purity, could you rank different sciences by how many digits of pi they require?

  • chayleaf
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    3 months ago

    I’m a programmer and I remember 33 digits, but in practice I never use pi because I never have to deal with geometry

    • josefo@leminal.space
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      3 months ago

      Game programmer here, lots of geometry. Usually 16 digits after the dot is ok. In graphics programming is also useful to define and use Tau (π×2), also defined to 16 digits