For real? I’ve never though of this. This may actually be useful!
% really just means
*1/100- it doesn’t matter where you apply that factor:6% of 50 = 6% * 50 = 6/100 * 50 = 6*50/100 = 6 * 50/100Where were you when I failed math 101 4 times?
Thanks!
I was probably on a different continent ^^ Also, the biggest problem explaining math is not making it understandable, but having a motivated learner. Most students that have a bad teacher in school, or are somehow not motivated in school to begin with, will also not be motivated to focus on easier explanations. Technically a basic interest in math should be fostered / encouraged in kids from an early age, and at the latest in elementary school. If that does not work out, many students will have a hard time with it.
You are welcome.
maths is the same in both case but I get it, for small numbers this is useful
Can we say “commutative” in this case ?
Yeah stuff like that really ain’t it. It works in a few use cases, but is objectively wrong and detracts from understanding the topic properly. That’s why I teach percentages as the fractions they are. By the time you learn percentages, you already know multiplying fractions is commutative, so the trick still works, and you also understand why.
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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.
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.
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.
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.
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.
And we should definitely short shrift the folks working for tips in the meantime.
Today I learned, thank you wise panzer
Wise panzer of the lake. There are other wise panzers, but they are malevolent, untrustworthy.
Most of the people explaining this still make it more complicated than it needs to be, imo.
I just think the symbol “%” algebraically means 0.01
6/100 * 50 = 50/100 * 6
6 * 1/100 * 50 = 50 * 1/100 * 6
it all equals 3
My dyscalculic ass trying to remember what 50% of 6 is
Probably 5 tbh
is tree fiddy
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.
.2*13=2.6
.03*13=0.39
2.6-0.39=2.21
My brain is maybe a weird place 😂
Same with 375% of 20 rather than 20% of 375.
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
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
Are you a “silent fartographer”?
No I think they specialise in medium or large format, with various filters… doing their own development with funky chemistry.
I don’t see this person as a black and white character. Very creative. Specialising in avant-garde still life maybe.
Seems pretty vocal to me.
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.
Hence 90% of 6 is still hard.
Not really tho. If you know 9x6=54 then it’s pretty easy to get to 5.4 from there
8 and 8 fell on the floor, picked it up, it was 74.
It’s because percent just means ×0.01 and multiplication can be rearranged
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.
commutable…
Surprised how many people don’t know this. I suspect it is because people forget that percent literally means per 100 or /100 and the of is standing in for multiplication. So 6% of 50 is 6/100 * 50 or 6 * 50 * 1/100
I have been looked at like a wizard saying “oh that’s just the amount times 1.2”
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
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.)
.5*23=11.5
0.01*23=0.23
3*0.23=0.69
11.5+0.69=12.19
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?
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.
Babagedegaga. Ba.
