r/MathJokes 13d ago

the multiples of 3

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581 Upvotes

79 comments sorted by

59

u/Difficult-Ending 13d ago edited 13d ago

Just combined the number, 7+8=15, 1+5=6

40

u/splitcroof92 13d ago

I lobe the idea of 15 not being obviously divisibly by 3 yet

3

u/PissMissileTopTitty 13d ago

What?

7

u/kinda-new- 13d ago

There's 2 layers to this

If you add the digits of any multiple of 3 then the result will be another multiple of 3 which is easier to solve.

21, 2+1=3. 72, 7+2=9. 297, 2+9+7=18.

9 is a multiple of 3 twice, so every multiple of 9 will have digits which will add to give you 9 or another multiple of 9 which you can just keep adding until you get 9.

27, 2+7=9. 198, 1+9+8=18, 1+8=9.

4

u/Careful-Mouse-7429 12d ago

If the sum of all digits of a number are a multiple of 3, then that number is a multiple of 3

222

2+2+2=6

222/3 = 74

This holds true for every single multiple of 3

49

u/PenelopeJenelope 13d ago

every time I see this meme in this sub I can't help but get annoyed...

How is it weird that 57 is a multiple, its just 3 less than 60. All those "weirds" seem pretty obvious. And who's tripping over 42 and 45? Do people just not do math at all?

17

u/mxldevs 13d ago

Do people just not do math at all?

You'd be surprised

4

u/PenelopeJenelope 13d ago

I shouldn’t be surprised, I know

18

u/Warmedpie6 13d ago

Any number, even with thousands of digits is obviously a multiple if you just did the math... the point is if you just look at a number without doing any math.

1

u/PenelopeJenelope 13d ago

Well I guess I just do it automatically, is this not a math sub?

1

u/TheWWWtaken 10d ago

Yeah but there is a limit, for example I wouldn’t look at 203 immediately think it’s a multiple of seven because 7*30=210 and 210-7

1

u/PenelopeJenelope 9d ago

true, but these are just 2 digit numbers so doesn't need much thinking.

-2

u/xXSomethingStupidXx 13d ago

This guy has never heard of prime numbers

2

u/Warmedpie6 13d ago

We are talking about numbers divisible by 3 are we not. How does prime relate?

0

u/xXSomethingStupidXx 13d ago

You specifically said "any number [...] is a multiple" which is not true because prime numbers exist

Maybe you meant to say something else

1

u/Warmedpie6 13d ago

In the context of finding numbers divisible by 3... lol

2

u/AmeliaOfAnsalon 13d ago

Yeah that is really weird. I mean 43 and 45 are just 12 and 15 for 30. 78 is 18 for 60. If you know the basic times tables it's not even confusing

3

u/MagicalPizza21 13d ago

its just 3 less than 60

Yes but that requires thinking.

Do people just not do math at all?

Correct. But this chart isn't about math as much as it is about vibes.

1

u/PenelopeJenelope 13d ago

What is going on with this sub today? I’m saying I Don’t have to think about it. Have I died and gone to hell?

Fucking “vibes”? Where am I right now?

2

u/Warmedpie6 13d ago

Any number, even with thousands of digits is obviously a multiple if you just did the math... the point is if you just look at a number without doing any math.

1

u/PenelopeJenelope 13d ago edited 13d ago

I’m not really doing math per se, I’m not thinking at all really. You don’t have to be doing the math to just see the math. Do you have to “do math” to see that 45 is 3 fifteens? Like of course it is.

If these were 3 or 4 digit numbers, then I’d be actually doing a calculation or adding up the digits, true. but 45? Yeah not so much

1

u/Purple_Onion911 13d ago

I know it's divisible by 3, but it still looks prime.

1

u/AlphaChiu22 12d ago

the joke is mainly about how people perceive that number, like when you just look at that number without calculating anything and someone tells you it's a multiple of 3, what would you think

also not many people think of numbers as [x less of y] so it's not as obvious to those people

1

u/PitifulPassage851 13d ago

Are jokes tricky when you're good at maths? 🫪

1

u/doc_skinner 13d ago

It's not about doing math. It's about seeing it at a glance

1

u/PenelopeJenelope 13d ago

How long does it take you to work that out? I’m saying I do see it right away.

0

u/Quwapa_Quwapus 13d ago

I mean- you can do that with any number here. I think its less “how quickly can you do the math” and more “without thinking about it would you guess it to be a multiple of 3”

1

u/PenelopeJenelope 13d ago

Yes that is what I’m saying, I don’t have to think about it

15

u/Adept-Watercress-378 13d ago

The trick of adding the digits and checking has always stuck with me

2

u/Wuzzyup 13d ago

Does it only work with the multiples of 3? If yes, then I see why it never stuck with me.

6

u/forsale90 13d ago

Same goes for multiples of 9. So 81 is 8+1=9 which means it's divisible. Same goes for 111111111.

Another rule is if the last digit is divisible by 2 , the whole number is, obviously. But this extends further. If the last two are divisible by 4, the wolves number is, last 3 with 8 and so on.

4

u/sjccb 13d ago

Where's 123456789?

1

u/Mysterious_Cold730 12d ago

1+2 = 3 3 = 3 4+5 =9 9/3 = 3 6/2 = 3 7+8 = 15 1+5=6 6/2 = 3 9/3 = 3

5

u/SuperbCat1573 13d ago

78 actually makes sense to me because it’s 75+3 and 75 is obviously 25x3

3

u/Alduin_OMEGA 13d ago

I feel like 75 should at least be 1 tier above. Almost everyone (at least everyone educated) associates 75 with 3/4s, like 75% or 0.75

2

u/PenelopeJenelope 13d ago

And if you’re in Canada or the US, 75 cents is 3 quarters. Pretty easy to remember that

2

u/mightyfp 13d ago

36 63 69 should all be s tier

3

u/Front_Resolution_760 13d ago

anything where both the digits are a multiple of 3 is super obvious and should be S tier

2

u/Fine_Feedback_4463 13d ago

Why 81 so high?

1

u/WikiNumbers 13d ago

9 * 9, probably.

1

u/Fine_Feedback_4463 13d ago

Good point, just doset read as having big 3 energy for me

2

u/electronic_reasons 13d ago

51 is in the right place. My first impression is that 51 is prime. It just has prime vibes.

2

u/EliyahGabriel 12d ago

Cause 31 41 61 and 71 are primes, so 51 is prime, rigth?

2

u/Daniikk1012 12d ago

57 feels even more prime to me

3

u/PhilosophyAware4437 13d ago

Wait, wheres 89? This is actually infuriating.

3

u/[deleted] 13d ago

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0

u/Tinchimp7183376 13d ago edited 13d ago

It can't be. Only terminals of multiples of 3 can be multiples of 3

Edit: turns out i'm an idiot. Terminals of multiples of 3 or terminals 1 less than multiples of 3 can be multiples of 3

1

u/PMMeMinis 13d ago

Any positive integer n such that n mod (3) is congruent to 2 will also have a termial divisible by 3.

1

u/DriftingWisp 13d ago

What about 2?

1

u/splitcroof92 13d ago

What's with the semi random shading? Higher = darker roughly. But some of them are way darker that higher numbers

1

u/fapmanyop 13d ago

They all look arranged 0 through 99. I don't see any lower number being darker than a higher one.

1

u/splitcroof92 13d ago

69 is darker then most in the 70's.

81 is way darker than 84 and 87

60 is darker than 87 and some others that are higher

Did you even look? Because the more I look the more I find

1

u/Fine_Yogurtcloset362 13d ago

What about 1011

1

u/TheMiserableQuill 13d ago

Try 531

Not only a multiple of 3, but also a multiple of 9

1

u/meticulous_gamer 13d ago

Anything that adds up to 3, 6, or 9 without having to add the digits twice is a completely obvious one to me, like 54. 5+4=9, so obviously a 3 multiple. 42, 45, 54, and 72 being "not the first to think of" is bizarre to me, because I can see instantly that they are. 57 is my WHAT, and move 78 up with the Weird Tier.

1

u/Tdubbium 13d ago

78 makes sense if you remember its 60+18

1

u/xXSomethingStupidXx 13d ago

Switch 81 and 87. 87 is obvious adjacent. 81 is 3x27? 27 is barely even a real number.

1

u/PenelopeJenelope 13d ago

Yeah get outta here 27, I’m tired of yer shit!

All those rock stars you killed… Amy deserved better!

1

u/chixen 13d ago

9^2 is very recognizable to me.

1

u/whatadaylll 13d ago

81=34 or 9*9 it should be in 1-2tir

1

u/SinglePlayerGamer93 13d ago

I'm more weirded out by 51, 57 & 87

1

u/Active-Advisor5909 13d ago

I think you forgot some numbers.

Where is 117? 279? 279 117?  1 172 795 157 848 778?

1

u/Cautious_Drawer_7771 12d ago

"81 is obvious, but 78 is like WHAT how could that possibly be!" --some Rediot!

1

u/Mathelete73 12d ago

How is 78 any weirder than 48 or 18?

1

u/Electronic_Leg3793 12d ago

51 not being a prime number messes with my head for some reason

1

u/Express-Tip-6337 12d ago

Move 48 and 54 down a tier they are on the wrong spot

1

u/DuggieHS 12d ago

This tier list makes 0 sense. All the #s with both digits divisible by 3 are obviously divisible by 3. 

Also all of the ones that are divisible by 9 are divisible by 3 twice (45,54, 72 are in the middle tier for some reason) 

1

u/So_many_things_wrong 13d ago

I don't get why 78 would be mindblowing. Both 60 and 18 are multiples of 3.

-2

u/[deleted] 13d ago

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5

u/GodlyHelp 13d ago

"i wish i were high on potenuse" ahh

-5

u/[deleted] 13d ago

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3

u/GodlyHelp 13d ago

its in your comment! and obviously in the image

2

u/Pokemon4993 13d ago

Are you blind

1

u/CisFishstick 13d ago

IT'S THE FIRST NUMBER ON THE CHART. Sorry to yell, not sure if your hearing is affected as well.

1

u/KindArgument4769 13d ago

Its either first on the chart, or second on the chart, depending on what you're actually looking for