This is far too useful to be a shitpost.
So wise.
Submitted 1 month ago by ObviouslyNotBanana@piefed.world to [deleted]
https://media.piefed.world/posts/sK/ub/sKubzRfAxxuLma0.webp
Comments
darkdemize@sh.itjust.works 1 month ago
Marthirial@lemmy.world 1 month ago
I know right. I even open the calculator app to verify before committing to memory this nugget.
idegenszavak@sh.itjust.works 1 month ago
Barely, only if you choose round and small numbers. 67% of 347 or 347% of 67 which one is easier?
MajinBlayze@lemmy.world 1 month ago
347 is pretty damn close to 350.
350% of 67 =3.5 x 67 ~ 180+21+33=234
Doom@lemmy.world 1 month 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 1 month 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 1 month 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 1 month 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 1 month ago
Good luck explaining your supreme methodology to anyone that isn’t a geek.
Proprietary_Blend@lemmy.world 1 month ago
Yo what
wander1236@sh.itjust.works 1 month 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 1 month ago
True
arctanthrope@lemmy.world 1 month 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 1 month ago
Percentages can be expressed as multiplication and multiplication is commutative (the order doesn’t matter).
DarrinBrunner@lemmy.world 1 month 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 1 month ago
Wait…
So 25% off $100… is 100% off $25! TrollfaceLordKitsuna@lemmy.world 1 month 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 1 month 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 1 month 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 1 month ago
4% x 7 = 4% x 100 x 7 ÷ 100 = 4 x 7 ÷ 100 = 28 ÷ 100 = 0.28
stickyprimer@lemmy.world 1 month 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 1 month ago
Everyone’s talking about this math. I’m wondering about the panzer.
Jankatarch@lemmy.world 1 month 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 1 month 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 1 month 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 1 month 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 1 month ago
Wait, you think 0.07 * 250 is easier than 2.5 * 7?
taiyang@lemmy.world 1 month 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 1 month 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 1 month ago
This one irks me to no end.
Botzo@lemmy.world 1 month 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 1 month 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 1 month 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 1 month 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 1 month 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 1 month 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 1 month ago
Or just take 10% of 138.72 and double the result… 13.87 x 2 = 27.74
SnarkoPolo@lemmy.world 1 month ago
True mathematics derives from established mathematical theory, not some farcical aquatic armored vehicle!
ArtVandelay@lemmy.world 1 month ago
Help help I’m being irrationalized!
JackTea@piefed.world 1 month ago
Oh panzer of the lake, why am I still single?
MonkderVierte@lemmy.zip 1 month ago
Are you sure you can bear the answer?
_thebrain_@sh.itjust.works 1 month ago
How is 17% of 83.27 easier then 83.27% of 17?
MrEff@lemmy.world 1 month 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 1 month ago
I hate math so much.
Thank you for thismelsaskca@lemmy.ca 1 month ago
It was recently discovered that all AI everywhere was connected to the Panzer all along. /s
SpankyDoodle@eviltoast.org 1 month ago
In either case I would multiply 5 by 6 and move the decimal. Interesting though.
JackbyDev@programming.dev 1 month ago
6 of 50 is 300. % just means 1/100. That’s also a good way to think of it.
justme@lemmy.dbzer0.com 1 month ago
transitive
Bluewing@lemmy.world 1 month ago
Subtraction and division is a lie! Only addition and multiplication are the truth!
eigenraum@discuss.tchncs.de 1 month ago
and, of course, only natural numbers may be used, excluding zero
starik@lemmy.today 1 month 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 1 month ago
twinnie@feddit.uk 1 month ago
This is probably only useful when you’re finding percentages of 50 or 100.
Omega_Jimes@lemmy.ca 1 month 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 1 month ago
Thanks tanks!
JoShmoe@ani.social 1 month ago
Panzer: Going tip to tip changes meaning the larger one of the participates is.
GioGioMioGio@feddit.org 1 month 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 1 month ago
To good of advice to be a shitpost
sinematic@lemmy.zip 1 month ago
Holy shit you solved my life there
negativenull@piefed.world 1 month ago
Pudutr0n@lemmy.world 1 month ago
Surely you don’t think supreme executive power derives from a mandate from the masses?
rockSlayer@lemmy.blahaj.zone 1 month ago
As opposed to what, a farcical aquatic ceremony?
wonderingwanderer@sopuli.xyz 1 month ago
I thought we were an autonomous collective