• Alenalda@lemmy.world
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        4 hours ago

        When I was young I learned that when you add up all the numbers if that number is a multiple of 3 than the original number is also divisible by 3. So 51, 5+1=6 and 6 divisible by 3 and so must 51.

    • juliebean@lemm.ee
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      1 day ago

      Grothendieck’s Prime tripped me up in a maths competition in high school. i had manually stored a list of primes in my calculator, and one of the puzzles involved primes and deducing the combination to a lock from certain clues. my list of primes erroneously included 57, which almost made my team fail the level, until i realized my error.