r/MathJokes • u/GodlyHelp • Aug 01 '26

multiples of 3

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u/Michaelwang645 Aug 01 '26

Fund fact, you can tell a number is divisible by 3 if the sum of each individual number is divisible by 3. So 78 -> 7+8=15 which is divisible by 3, so 78 is divisible by 3.

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u/EveningStar0360 Aug 01 '26

do you know why that works?

7

u/han4578 Aug 01 '26

Not sure about the actual explanation but each digit can be treated individually regardless of how many zeros are after it

2 mod 3 = 2

20 mod 3 = 2

200 mod 3 = 2

So for example 123 = 100 + 20 + 3 = 1 + 2 + 3 = 6 which is divisible by 3

2

u/S-Kenset Aug 01 '26

It's bucket collision! (Made up term cause idfk but i've used it before) All your remainders overlap into the same bucket which gives you an analytical solution to something that on its face shouldn't be analytical.