This is blowing my fucking mind like an artillery shell
Yeah, I personally find it a lot easier to compute 13% of 17, rather than 17% of 13.
Same with 375% of 20 rather than 20% of 375.
Damn, it still worked. Holy shit.
The few times I’ve seen you on Lemmy, it takes me a few seconds to process your username. Today, I had my favorite misreading yet: pronounced Ivana footerall
Thanks, now I can’t unsee that, fartographer
Actually I disagree.
20% is 1/5
100/5=20
10/5=2
5/5=1
3*20=60
7*2=14
1*1=1
60+14+1=75
.2*13=2.6
.03*13=0.39
2.6-0.39=2.21
My brain is maybe a weird place 😂
I guess it’s easy to miss that m% just means ×m÷100
6% of 50 means 50 × 6 ÷ 100, and because multiplication and division have the same order of operations you can switch them around. so it is also equal to 6 × 50 ÷ 100, in which you can simplify 50 ÷ 100 into 1 ÷ 2, but you could always do that: 50 × 6 ÷ 100 = 1 × 6 ÷ 2.
this “shortcut” however is of extremely limited use. basically for taking a percentage of anything other than things that can very easily divide or multiply 100 like 50 in this example or maybe 10 or 500 it’s nearly useless.
It’s because percent just means ×0.01 and multiplication can be rearranged
x/100 * y = x * 1/100 * y = x * y/100
I never would have thought of it myself and still feel like I should have thought of it myself.
So 37 % of 38 is equivalent to (37 * 38 ) / 100 ? Which I can almost do in my head.
37 * 4 is 148 I think, so 37 * 40 is 1480. Subtract 74 we have 1406. So we have 14.06?
You’re hired
For a while I’ve been meaning to memorize all the two digit squares but of course I then fail to practice them, so I’m not very far along. But that would help you with this too, not to mention you can start doing some square roots too.
For quick and dirty I’d probably just go with
37*38 = 40*40 -> 16%which is kinda close to 14% eh?Oh absolutely, depends on what you are measuring if that isn’t close enough
For quick and dirty I’d probably just go with 3738 = 4040 -> 16% which is kinda close to 14% eh?
Quick and dirty and accurate is 38=40-2. So 38x37=(40-2)x37=40x37-2x37=1480-74=1406
This is great. I won’t remember it when I will need it.
Just save the meme in the maths folder!
You clearly don’t have gigs of memes.
You shut your whore mouth
23% of 53
53% of 23, next question
Pretty close to 1/4 of 52, so like 13-ish, but maybe closer to 12.
(13 + 0.25 - 0.53 - 0.53, really. If I had to, I might be able to keep that in my head.)
May as well just get out the calculator app to make sure. My point with those numbers is to just use a calculator. Why 2nd guess anything?
May as well just get out the calculator app to make sure
Calculator apps get order of operations questions wrong because of programmers who were too lazy to check they had their Maths correct
My point with those numbers is to just use a calculator.
My point is avoid calculator apps like the plague. Use name brands like Sharp or Casio.
Why 2nd guess anything?
Guess what the programmer of your calculator app did 😂
If “close enough” works, then it’s nice to have the skill. Having the skill requires occasionally using it.
Where accuracy is important, since we almost always have a calculator with us now, that’s a no-brainer.
Maybe more to the point, though, understanding how percentages work is wise. It’s one of the few arithmetic topics that we encounter regularly in life.
In this case, 23% of 53 and 53% of 23 each have their own little trick, depending whether you’d rather overestimate a little with 1/4 of 52 or underestimate a little with half of 24. I find it handy to be able to think that way, especially for example when trying to get out of a taxi and paying cash.
Where accuracy is important, since we almost always have a calculator with us now, that’s a no-brainer.
Unfortunately most calculator apps were written by no-brainers who didn’t check they had their Maths correct. If you need accuracy then get a name brand like Sharp or Casio.
.5*23=11.5
0.01*23=0.23
3*0.23=0.69
11.5+0.69=12.19
Babagedegaga. Ba.
My dyscalculic ass trying to remember what 50% of 6 is
Probably 5 tbh
I’m gonna track down all my HS math teachers and punch each and every one of them in the mouth.
I’m gonna track down all my HS math teachers and punch each and every one of them in the mouth.
Understandable if you’re in the U.S., where Maths teachers don’t have to have any Maths qualifications. Other places, where you do have to have Maths qualifications, we teach this.
Legitimately new knowledge for me that will literally make my work easier. Wish I could give you more than 100% of 1 upvote, OP!
I wish someone told me this trick 30 years ago.
1 of 100% upvote. Yeah, it checks out!
6*50/100 = 50*6/100 if anyone is curious why this works.
Or, more generally:
Taking X percent of something is the same as multiplying by X/100.
X percent of Y = Y(X/100)=(YX)/100
Y percent of X = X(Y/100)=(XY)/100
(YX)/100=(XY)/100
Percentages are indeed reversible.
Yes, 47% of 47 is certainly much easier to determine when you look at it as 47% of 47! Genius!
Yes, 47% of 47 is certainly much easier to determine
And your real life example of a 47% discount on a $47 item is… where exactly?
Teaching stats and using percentages now and again, it’s not really that useful of a tool most of the time since you aren’t usually working with an easy number like 50 (Or 10, 20, 25, etc.).
Usually what I’m doing is breaking it down into manageable parts (factors), so 6% is 5% + 1% which I can usually do in my head regardless of the number (or if 5% hard, work in increments of 1%, which I can multiply by 6).
It’s a pretty common strategy to with with factors. Just surprised how many of my students don’t know it!
Huh. Learning a fun and cool math trick was not on the list of expected outcomes for today, but I’ll take it!
commutable…
Sweet, thanks Panzer of the Lake!
Danke
This is the coolest trick since I learned about the “quick 20% tip on your tab” method. Take the total bill, move the decimal point one place over to the left, then multiply it by 2 to get 20% gratuity. I will sometimes round down on the change to make it closer to 18%. Also I only really need to do this when I’m drunk and can’t maths.
Why would you multiply by 2? 10% is a good tip.
As long as wages are supplemented by customers, the restaurant industry will never pay their employees a fair wage.
10% is in fact, not a good tip, despite your misplaced morals. You think by stiffing servers that restaurants will care? Do you honestly think that will make a difference, or are you just cheap? Build the cost of a tip into what you expect to pay for a meal out or don’t eat out. Tip culture sucks but it’s the standard and you don’t have to like the standard but fix it at the ballot box, not at the dinner table.
10%s a shit tip, work a year in service and say that
I did my time in the industry. I left it for a reason.
As a former service worker,
- fuck you
- this is NOT solidarity
- bosses won’t pay more because you pay less
- pay tips in cash. PAY TIPS IN CASH IF POSSIBLE
Why cash? So you can split my $5 with the other 20 staff members? Or so you can hide it from your team? If your boss is taking money from the tip pool paid through card transactions that’s illegal. You are forcing industry problems onto the customer and frankly it’s not my problem. I feel bad for you but all I have are likes and prayers. I’m not gonna let employees who are scared to hold their employers accountable to guilt trip me into giving them my money. 10% is extremely reasonable considering the standard for service in restaurants right now. I can’t remember the last time I didn’t have to go find a staff member to get a refill.
In restaurant cash isn’t always as important. However the boss/power dynamic and employment laws can mean service workers are often left with little to no bargaining power.
Cash is more important for food delivery services so the company doesn’t take a majority cut. Though, judging by your statements, I’m guessing you feel insulted by the very idea of tipping for delivery.
“Little to no bargaining power” doesn’t mean anything. You hold your boss accountable to treating you fairly. I met a kid that last year worked in a cash only Vietnamese sandwich shop. Only white kid there. He essentially unionized the place and stopped the owner from stealing their tips.
If a 20 year old can stand up to person like that when he can barely speak the language, I don’t want to hear about how a group of Americans who don’t have to fear of getting deported or send any money back home to feed their family struggle in the work environment.
It really sounds like a crazy story but he did it and probably changed some of those workers lives. And don’t even get me started on delivery fees that for whatever reason the workforce agreed shouldn’t be paid to them.
Neat, good for that kid!
I don’t like tip culture either, but I’m not going to stiff the guy making federal minimum wage.
If I’m drunk and having a good time, 20% seems fair to me. You can pay whatever you think is fair, I’m not passing judgement on that account.
Yeah, no one wants to be that guy, so here we already are tipping.
