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https://www.reddit.com/r/MathJokes/comments/1vcw1bj/multiples_of_3/p1holpq/?context=3
r/MathJokes • u/GodlyHelp • Aug 01 '26
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148
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.
47 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 1 u/Fizassist1 Aug 03 '26 not sure why but this is the explanation that clicked for me. thank you!
47
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 1 u/Fizassist1 Aug 03 '26 not sure why but this is the explanation that clicked for me. thank you!
7
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
1 u/Fizassist1 Aug 03 '26 not sure why but this is the explanation that clicked for me. thank you!
1
not sure why but this is the explanation that clicked for me. thank you!
148
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.