• sugar_in_your_tea
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    1 month ago

    For me:

    3974 * 438 -> 4000 * 438 - 26*438 ->
    4000 * 438 - 26*440 - 26*2 -> 4000 * 438 - 20*440 - 6*440 - 26*2
    

    And so on, and I’d do some of the intermediate calculations as I go (e.g. 20*440 and 6*440).

    But that’s only really needed if I need a precise answer. If I can get away with an estimate, I’ll simplify it even more:

    4000 * 430 ~= 43 * 4 * 10000 = 86 * 2 + 10000 = 1,720,000

    Actual answer: 1,740,612. 4000 * 440 would be easier (I like multiplying 4s), but I know it would overshoot, so I round one up and the other down. Close enough for something like estimating how much a large quantity of something kind of expensive would cost (i.e. if my company gave everyone a hot tub or something).