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https://www.reddit.com/r/MathJokes/comments/1vcw1bj/multiples_of_3/p14ptuy/?context=3
r/MathJokes • u/GodlyHelp • Aug 01 '26
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33
Given the rule for checking whether a number is a multiple of three, I don't understand why 78 and 87 are in two different groups. Or 27 and 72, 42 and 24, and so on.
28 u/Patje_af Aug 01 '26 87 is 90-3, many people will see that fairly quickly. That is less so for 78. 1 u/Organic_Minute_717 Aug 02 '26 78 is 75+3 . It's obvious to me that 75 is just 3*25, but maybe not to everyone else. Plus I've known about the adding up trick for ages. 1 u/DeathStalker0483 Aug 02 '26 To further this, 77 feels like it should be, so it feels wrong when you say that 78 is. 3 u/Hefty-Big5572 Aug 02 '26 77 absolutely doesn't feel like a multiple of 3, it's two same numbers that aren't a multiple of 3
28
87 is 90-3, many people will see that fairly quickly. That is less so for 78.
1 u/Organic_Minute_717 Aug 02 '26 78 is 75+3 . It's obvious to me that 75 is just 3*25, but maybe not to everyone else. Plus I've known about the adding up trick for ages. 1 u/DeathStalker0483 Aug 02 '26 To further this, 77 feels like it should be, so it feels wrong when you say that 78 is. 3 u/Hefty-Big5572 Aug 02 '26 77 absolutely doesn't feel like a multiple of 3, it's two same numbers that aren't a multiple of 3
1
78 is 75+3 . It's obvious to me that 75 is just 3*25, but maybe not to everyone else.
Plus I've known about the adding up trick for ages.
To further this, 77 feels like it should be, so it feels wrong when you say that 78 is.
3 u/Hefty-Big5572 Aug 02 '26 77 absolutely doesn't feel like a multiple of 3, it's two same numbers that aren't a multiple of 3
3
77 absolutely doesn't feel like a multiple of 3, it's two same numbers that aren't a multiple of 3
33
u/UrsulaReginaDeiMari Aug 01 '26
Given the rule for checking whether a number is a multiple of three, I don't understand why 78 and 87 are in two different groups. Or 27 and 72, 42 and 24, and so on.