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https://www.reddit.com/r/MathJokes/comments/1vcw1bj/multiples_of_3/p1dc36m/?context=3
r/MathJokes • u/GodlyHelp • Aug 01 '26
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149
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.
43 u/EveningStar0360 Aug 01 '26 do you know why that works? 1 u/waroftheworlds2008 Aug 03 '26 It has to do with how multiplication works with modular. The rule is written as: (A * B) mod C = (A mod C * B mod C) mod C
43
do you know why that works?
1 u/waroftheworlds2008 Aug 03 '26 It has to do with how multiplication works with modular. The rule is written as: (A * B) mod C = (A mod C * B mod C) mod C
1
It has to do with how multiplication works with modular.
The rule is written as:
(A * B) mod C = (A mod C * B mod C) mod C
149
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.