This is far too useful to be a shitpost.
So wise.
Submitted 3 weeks ago by ObviouslyNotBanana@piefed.world to [deleted]
https://media.piefed.world/posts/sK/ub/sKubzRfAxxuLma0.webp
Comments
darkdemize@sh.itjust.works 3 weeks ago
Marthirial@lemmy.world 3 weeks ago
I know right. I even open the calculator app to verify before committing to memory this nugget.
idegenszavak@sh.itjust.works 3 weeks ago
Barely, only if you choose round and small numbers. 67% of 347 or 347% of 67 which one is easier?
MajinBlayze@lemmy.world 3 weeks ago
347 is pretty damn close to 350.
350% of 67 =3.5 x 67 ~ 180+21+33=234
Doom@lemmy.world 2 weeks ago
I was taught: IS over OF, PERCENT over 100.
Is/of × %/100
Is = x
Of = 347
Percent = 67X/347 × 67/100
Multiply 347×67=23, 249
Divide by 100232.49 is 67% of 347.
ColeSloth@discuss.tchncs.de 3 weeks ago
it’s very often not useful. Like, what’s 6% of 80? See. Still hard.
Also, with the 6% of 50 example it’s easy without using this trick.
What’s 6% of 100? 6, right? So cut 100 in half to get to 50, and cut the 6 in half to get the 3. Cut the 50 in half again and cut the 3 in half again, and you’ll also know that 6% of 25 is 1.5.
Which also lets you know that 6% of 75 is 4.5. the 3 from the 50, plus the 1.5 from the 25. or just know to split the difference between the 3 at 50 and the 6 at 100.
A lot of math is just tricks for a thinking process.
starik@lemmy.today 2 weeks ago
It’s always as easy as multiplying the two numbers. Just convert the percentage to a fraction.
0.06x80 is just as easy as 0.8x6. It’s just a matter of knowing 6x8 is 48, which quickly gets you to 4.8 here.
Atomic@sh.itjust.works 2 weeks ago
6% of 80. 1% of 80 is 0.8 0.86 is (86)/10 Which is 48/10 = 4.8
80% of 6. I’d probably think of it as (4/5)*6 = 24/5 Which is 20/5 + 4/5 = 4 + 4/5 = 4.8
Both are easy if you know how to visualise it. The benefit of knowing you can “reverse” it is that you can choose which method is easier for you to visualise. Which is incredibly useful for a lot of people
ddplf@szmer.info 2 weeks ago
Good luck explaining your supreme methodology to anyone that isn’t a geek.
Proprietary_Blend@lemmy.world 3 weeks ago
Yo what
wander1236@sh.itjust.works 3 weeks ago
Multiplication is commutative.
50% of 6 == 50/100 x 6 == (50 x 6)/100 == 50 x 6/100 == 6% of 50.
S_H_K@lemmy.dbzer0.com 3 weeks ago
True
arctanthrope@lemmy.world 3 weeks ago
taking x% is just multiplying by x/100, and multiplication is commutative. x% of y is just y×x×1/100, which is the same as x×y×1/100
you can also ignore the % and divide by 100 at the end. for example, what’s 5% of 5? that might take a minute to work out. what’s 25/100? you instantly know it’s 1/4
red_bull_of_juarez@lemmy.dbzer0.com 3 weeks ago
Percentages can be expressed as multiplication and multiplication is commutative (the order doesn’t matter).
DarrinBrunner@lemmy.world 3 weeks ago
Let’s try this on a sale item. Hmm, let’s see, the sign says 25% off $6.99. So that’s the same as, let’s say, 7% off $25. Oh, yeah, that is much easier. /s
sneezycat@sopuli.xyz 3 weeks ago
Wait…
So 25% off $100… is 100% off $25! TrollfaceLordKitsuna@lemmy.world 3 weeks ago
I mean if you remove the word off it works. 25% off $100 is $25 100% of 25 is 25 it’s still reversible you just let the word off confuse you
starik@lemmy.today 2 weeks ago
It’s always as easy as multiplying the two numbers. Obviously some pairs are easier than others. 7x25=175. Not too hard. $1.75 off.
stickyprimer@lemmy.world 2 weeks ago
Fuck. I had to calculate 4% of 7 a few minutes ago and didn’t know this. I say fuck because it wouldn’t have helped me anyway.
incogtino@lemmy.zip 2 weeks ago
4% x 7 = 4% x 100 x 7 ÷ 100 = 4 x 7 ÷ 100 = 28 ÷ 100 = 0.28
stickyprimer@lemmy.world 2 weeks ago
My brain was more like “Okay it’s just seven point-fours. So what’s seven fours? 28. What’s seven point-fours? 2.8. That can’t be right. Fuck. Get a calculator.
jaybone@lemmy.zip 3 weeks ago
Everyone’s talking about this math. I’m wondering about the panzer.
Jankatarch@lemmy.world 3 weeks ago
They said the water could reach up to 50% of its 1.7 meter height before causing problems, panzer tried calculating 1.7% of 50 meters from head, this is the result.
hperrin@lemmy.ca 3 weeks ago
6% of 50
6/100 * 50/1
(6 * 50) / (100 * 1)
(50 * 6) / (100 * 1)
50/100 * 6/1
50% of 6
Works for multiplying any fraction, not just percents.
2/3 of 5 is the same as 5/3 of 2.
2/5 of 7/8 is the same as 7/5 of 2/8.
taiyang@lemmy.world 3 weeks ago
I was waiting in a car in front of a math tutoring building and was doing the math programs advertised on their window (as one does, of course) and the 7% of 250 is indeed probably easiest as 250% of 7, aka 2.5x7, which is 17.5.
I did it a few other ways, though. 7% of 1000 is 70, then divide by 4 for 17.5. Well, more like, divide by 2 for 35 and again for 17.5, but yeah… mental math is fun.
BewareOfIdiot@nord.pub 2 weeks ago
I …. and the 7% of 250 is indeed probably easiest as 250% of 7, aka 2.5x7, which is 17.5.
BewareOfIdiot@nord.pub 2 weeks ago
Wait, you think 0.07 * 250 is easier than 2.5 * 7?
taiyang@lemmy.world 2 weeks ago
Huh, no, I was saying the opposite. But there are easy alternatives aside from 0.07 x 250, like (0.07 x 1000) / 4.
kryptonianCodeMonkey@lemmy.world 3 weeks ago
A 10 percent discount and a 10 percent fee can be calculated in either order but they don’t cancel out.
Example, 90% of (110% of 10) = 110% of (90% of 10). But neither of those is evaluates to 10. It evaluates to 9.9.
For any percentage X, and and base value C,(100 - X)% x ((100 + X)% x C) = (100 + X)% x ((100 - X)% x C) = (100 - (X^2/100))% x C
JackbyDev@programming.dev 3 weeks ago
This one irks me to no end.
Botzo@lemmy.world 3 weeks ago
Great for calculating tips!
Let’s see: the bill was $138.72, so I just need 138.72% of 20. And we can subtract 100% and just add the 20 back at the end, then convert the percentage to a decimal so (.3872 * 20) + 20 = 7.744 + 20 or $27.74.
Easy!
snooggums@piefed.world 3 weeks ago
I prefer taking 10% and doubling it for a 20% tip.
Take the total, moved the decimal one digit to the left, double it and round to the nearest dollar. I round up at the beginning and end as well which is either close enough or a dollar high if the change is small enough.
$138.72 > 139 > 13.9 > 27.8 > $28
Close enough!
valar@lemmy.ca 3 weeks ago
I either do this, or mentally divide by 5 (how many 5s make this number?), only caring about the closest whole number - I prefer to tip in whole dollar amounts to make the math easy.
Eg. $39.53 is about $40, 40 is 8 fives, so tip $8
Catoblepas@lemmy.blahaj.zone 3 weeks ago
I always just do 10% (easy because you move the decimal one place) and then either double that or add half of it to itself for a 15-20% tip.
Botzo@lemmy.world 3 weeks ago
For sure. Reversing the percentages here makes this far more difficult. I just felt we needed to shittify this post a little.
Waterpumpee@lemmus.org 3 weeks ago
i just do 0. I feel like giving 20% more than agreed upon as default is crazy. I can not imagine employers giving 20% more wages just because i was doing my job? Why should i burn money?
Neverclear@lemmy.dbzer0.com 2 weeks ago
Or just take 10% of 138.72 and double the result… 13.87 x 2 = 27.74
SnarkoPolo@lemmy.world 2 weeks ago
True mathematics derives from established mathematical theory, not some farcical aquatic armored vehicle!
ArtVandelay@lemmy.world 2 weeks ago
Help help I’m being irrationalized!
JackTea@piefed.world 2 weeks ago
Oh panzer of the lake, why am I still single?
MonkderVierte@lemmy.zip 2 weeks ago
Are you sure you can bear the answer?
_thebrain_@sh.itjust.works 3 weeks ago
How is 17% of 83.27 easier then 83.27% of 17?
MrEff@lemmy.world 3 weeks ago
Oddly, yes.
Percentages also add together in partials. As in 10%+5%+2% = 17%
So, you start with the 10% by moving the decimal over 83.27 becomes 8.327
Then add half of that (5%) to its self and get 12.49 (rounded)
Then take the 10% number and move the decimal over once more (1%) for 0.833 and double it (from 1% to 2%) and get 1.666 and add that to your running total to get your answer of 14.16 (rounding)
And when I calculator check this I got 14.1559.
TachyonTele@piefed.social 3 weeks ago
I hate math so much.
Thank you for thismelsaskca@lemmy.ca 2 weeks ago
It was recently discovered that all AI everywhere was connected to the Panzer all along. /s
SpankyDoodle@eviltoast.org 3 weeks ago
In either case I would multiply 5 by 6 and move the decimal. Interesting though.
JackbyDev@programming.dev 3 weeks ago
6 of 50 is 300. % just means 1/100. That’s also a good way to think of it.
justme@lemmy.dbzer0.com 2 weeks ago
transitive
Bluewing@lemmy.world 2 weeks ago
Subtraction and division is a lie! Only addition and multiplication are the truth!
eigenraum@discuss.tchncs.de 2 weeks ago
and, of course, only natural numbers may be used, excluding zero
starik@lemmy.today 2 weeks ago
Just always convert the percentage to a decimal, and it’s easy either way.
0.06x50 is as easy as 0.5x6. They’re both just 5x6.
All these comments like “What about 47% of 3.11?” Well, yeah, of course it’s harder to multiply two- and three-digit numbers than it is to multiply single-digit numbers.
sinematic@lemmy.zip 2 weeks ago
twinnie@feddit.uk 3 weeks ago
This is probably only useful when you’re finding percentages of 50 or 100.
Omega_Jimes@lemmy.ca 3 weeks ago
No way! 68% of 120 is 120% of 68, so drop the 100% now i just need to figure out 20% of 68 or do i need 68% of 20 which is really just 6 tens plus 8% so divide 20 by 10, then times 6 which is 12, now we need 8% of 20 which is just 20% of 8 or whichdies
ShotDonkey@lemmy.world 2 weeks ago
Thanks tanks!
JoShmoe@ani.social 3 weeks ago
Panzer: Going tip to tip changes meaning the larger one of the participates is.
GioGioMioGio@feddit.org 3 weeks ago
the % sign just means 1/100 or 0.01.
so 6% * 50 = 6 * 0.01 * 50
and since you can rearange factors:
= 6 * 50 * 0.01 = 6 * 50%
Megamanexent@lemmy.zip 3 weeks ago
To good of advice to be a shitpost
sinematic@lemmy.zip 2 weeks ago
Holy shit you solved my life there
negativenull@piefed.world 3 weeks ago
Pudutr0n@lemmy.world 3 weeks ago
Surely you don’t think supreme executive power derives from a mandate from the masses?
rockSlayer@lemmy.blahaj.zone 3 weeks ago
As opposed to what, a farcical aquatic ceremony?
wonderingwanderer@sopuli.xyz 3 weeks ago
I thought we were an autonomous collective