Taking percentages

[R3ACHVEVO]

hi if you have time to answer my question it would be really helpful so my question is that i don't know how to take percentages for example ''Decrease $5 by 15%''

and i have no clue how to do it and i can't understand the way my math teacher explains so if you have time it would be very nice thanks continue making great and simple videos thanks :)

[angeltheya12]

@R3ACHVEVO idk if this answer is still valid (since its been 5 days ago) anyways you can solve that problem by first taking 15% of $5 . Basically how much is 15% in $5. Convert 15% to decimal which is .15 then multiply it by $5. The answer will give you 0.75 dollars the 15% of $5. Minus/decrease $5 by $0.75 and you will get the answer u r looking for. $4.25

[MrMGD92]

to get the % of any number just divide the number by 100 and times it by the number your looking for the % of.So 15% of 40 to get that anwser khanacademy did 15 divide by 100 but left off the zero in his answer so its 0.15 but he wrote .15 and x that by 40.

[TheSoopahG]

I love you

[BizzyKids315]

thx for all the help.111

[DarkSamurai305]

your better then my teacher

[TheComedydude1]

Here is a question... William has 118 dollars in the bank. Yesterday, he had 67 dollars in the bank. By what percentage did William's bank account increase over the past day?

Answer this and I'll tell you the answer!

[MrMGD92]

@TheComedydude1 Is the answer 79.6?

[PvMRay]

Thank you.

[Akatasuki21]

4 people disliked this. They are the teachers who are jealous because they can't teach like Sal XD

[kcutari]

@axxomint

U are correct

[Axxomint]

4 is 20% of what number ?. my calculation would be 100 / 20 * 4 which equals 20

[ScarfifyMadge]

Thank you so much for all of the work you do. Every time I have end of the year exams I come back here to study up. You've really helped me pass some tests I probably wouldn't have if I didn't study here!

[SamLaPoint]

i wish all teachers had a calm and normal voice instead of a monotone voice, it makes it easier to listen to and pay attention

[joshwaggoner14]

i am going to pass the asvab now you have everything i need to study ad its like im in school =DDDD

[mohabbat66]

i love you ur the best. i never thought math would be this easy

[DarthLegostopmotions]

thanks so much for your help on algebra i have a huge test to take and i'm almost ready to tackle any challenge they throw at me

[DarthLegostopmotions]

thanks so much i have a huge test on algebra tomorrow and your different perspectives on the questions helped me understand some of the practice problems easier

[mtn02662]

Seriously man, this channel is a life saver. Been out of high school for about 6 years, and i literally DUMPED all this basic stuff out of my head. This is a great refresher, and this guy is a great teacher.

[vickiormindyb]

When you're doing IV Therapy, you're always supposed to put 0's to the left of any point. So I'm used to seeing 0.2% and 0.002.

Doctors insist on the 0 before the point, b/c a patient almost died after a nurse didn't see the point in .25 and gave the patient 25 mg instead of 0.25 mg.

All the doctors told us there's a gigantic difference between 25 mg and 0.25 mg.

[uphill248]

this didnt help me. can someone help me please? if i get a 2% cash back on $19.40. how much am i getting back?

[kozes]

@uphill248 your comment was about a month ago, so you might have figured it out already.

i think this is what you are asking 19.40 + 2%.  2% = 0.02

0.02 x 19.40 = 0.388

so 0.388 is what you are getting back on 2%

[vickiormindyb]

My newest friend can see all these numbers in his head, I'm talking to the point of actually upsetting the cashier who was totting up his groceries.

He arrived at the answer just before the machine did.

[ukandoittowithkandoo]

Man i started a sales advisor job last mon and i can't eeven figure out how to take 20% off a price i am fuckedci tell ya.

[Inaflap]

@ukandoittowithkandoo

The quickest way to deduct 20% is to multiply the figure by 0.8.

That is 1 – 0.2 = 0.8. Where the 1 is the original figure and the 0.2 is the 20% you deduct.

e.g. To deduct 20% from something costing £25 just multiply the 25 by 0.8.

0.8 x 25 = 20 so £25 less 20% equals £20.

To add 12% to £30 say... then you can multiply by 1.12. 1 (the original amount) + 0.12 (12%).

1.12 x 30 = 33.6 so £30 plus 12% equals £33.60.

[YoungDrewTV]

@Inaflap nerd...:D

[xXKam21Xx]

Great teaching, very easy to understand. And you have a nice voice. ;)

[xXKam21Xx]

Great teaching, very easy to understand. And you have a nice voice. ;)

[JennaCides]

You've helped so much! thank you!! you were very easy to understand!

[kalimbalimCAPS]

I wish you were my math techer back in school.

[HunnyKidd1973]

This is the problem that I keep getting stuck on...

Find a number so that 70.9% of it is 78.

I really don't know how to go about working this. It is not the same the generic

"What is 89.1% of 107"?

Can you please help me?

[UnwelcomedStranger]

@HunnyKidd1973 Those are the 3rd and fourth equations he does with different wording. Basically you are looking for a number (x) that multiplied by a given percentage, equals the given number. SO, for your "Find a number so that 70.9% of it is 78." Turn "a number" into x, then you have "X multiplied by 70.9% is 78" or ".709x = 78" divide both sides by .709 and you get "x=78/.709 (x=110.014...)" Hope that makes sense/helps.

[HunnyKidd1973]

@UnwelcomedStranger Thank you so much, you don't know how much you have helped me.

[deepakjindal070]

most complicated khan video..

[ukarcu]

Thank You Khan!

You are the best teacher I have seen! You have helped me SO MUCH!!!!!

...but... ...in this case I think it is going to be better thinking on % as it is a proportion, so, "3 is to x as 9 is to 100" or "3:x as 9:100" or "3/x = 9/100" ...

I think this is the easier way.

THANKS A LOT!!!!!!!!!

[milehibass]

Do you have any videos about converting liters, ml, kg, etc.? I begin dosage calculations soon and would love to have some additional help other than our book. Thank you

[useurcamera]

i wanna be your student

[jzellner12]

His method is okay to use, but I find that if you use the equation is/of = %/100, it is much easier...

4 IS 20% OF what number?

take it phrase by phrase...

4 IS...4 goes in the numerator, per the equation,

OF what number...x goes in the denominator, per the equation...and then put the percentage number over 100 and you get 4/x = 20/100...solve for x and get 20! :)

[icarax1999]

I am taking the ISEE's this year and its helped me prepare SO much. Thanks!!!

[onse212]

thank you khan academy!!!!!

[Djcrazykidd]

what about a percent that is 8.27% what is that conversion

[asmodeus585]

@Djcrazykidd: What do you mean? 8.27% is 0.0827. If you want to find 8.27% of a given number x, then you just multiply 0.0827 times x. When number a is 8.27% of x then you divide a by 0.0827 to get x.

[Djcrazykidd]

@asmodeus585 OH NO NO NO NO NO, I its cool I know now, that comment was old,...little late to explain don't you think?

[asmodeus585]

@Djcrazykidd: No, I don't, as I wonder how come anyone could not understand it in the first place. Since you didn't, I couldn't know if you eventually got it or not. Perhaps, if you could spell in proper English, I wouldn't bother asking what was that, what you wanted to know...

[MrRCOLA]

At 6:07 why did he divide by 2

[lanied57]

Very helpful. :)

[lanied57]

Thanks for making this you helped a lot of people. :)

Daniel 7th grader Hillview Middle School

I'm gonna tell my teachers about this. :D

[wizardofwit]

This might sound facetious, because I'm clearly thinking outside the math, more like metaphysically, but I can't stop wondering;

In the last example we find that 3 is 9% of 33.33333... and cetera. If the number is infinite though, how can it have a finite percentage? Is there in anything in the maths to show that, or explain it?

[idster7]

@wizardofwit i'd say the number is not infinite. it's 100/3.  it just has to be represented as infinite if written in decimal form.

[wizardofwit]

Doesn't the fact that one form of the number is infinite mean that they all are? The number doesn't simply become infinite when it's converted to a decimal. 100/3 is a finite representation of an infinite number.

A finite representation is just that, a representation. The lemniscate is a finite representation of infinity, just like a line over the decimal 3's represents their infinite nature.

[idster7]

@wizardofwit i would say no. there may be an infinite amount of numbers in aggregate, but one particular number is not "infinite". the difference between 100/3 in fraction form, and 100/3 in decimal form is that the fraction form requires only several figures to be exactly represented, whereas the decimal form gets ever closer to exactitude but does not achieve it, no matter how many figures are expressed.

[ARGblargARG]

finally! i can do my hw correctly ;D

[TehRoflBot]

tnx this is going to help me with the AMC 8 test

[shinzue1]

LOL ITS STILL HARD FOR ME.

[christiankmachnishow]

Thx for your help !!! i was a bit confused though ok but thx and wat you can do is wath my shows that will be a real help and advertise it ok bye !!!!!!1

[ZimDirect]

Is there a reason .2 becomes .002 (2 decimal points) ie Why not .02. Whats the reasoning behind the movement of decimal points (especially when dealing with single digits). Thanks

[theurgetoexplore]

that's because: if 15% = .15 then what would 2% equal? it would be .02 and so what would .2% be.....? it would be .002!

[NJmalibu313]

Zim,

Think about it, .2 would actually be .20 which is 20%.

So, .02 would be 2%, making .2% .002

[ThePakiShop]

it doesnt really matter mate as long as its a decimell 0.1 0.01 0.001 0.0001 etc its all the same once u go below 0

[musiklover2]

@zimdirect

To add to what theurgetoexplore said

think of 15% as 15.

think of 20% as 20.

Their decimal place come after the number and whenever you get a percentage, you must move the decimal two places to the left

so 15% which you should view as 15. becomes .15 when moved two decimals to the left & 20% which should be viewed as 20. becomes .20 when moved two decimals to the left.

So, using the same method .2 becomes .002 when moved to the left twice. Since it has no numbers, we use zeros.

[musiklover2]

@zimdirect

explanation continues-ran out of space. as I was saying, lol!

.2% becomes .002 & since it has no number after it, it shows the two decimal moves by the zeros.

some more examples

2% is viewed as 2.

moved two places to the left becomes .02

.02% moved two places to the left becomes .0002 So on & so forth.

Hope it makes sense to you now. I know that was months ago, may be by now u do get it but I figure I'll explain it anyway cause there might be others who can find this helpful.

[miser199]

you can also use the perportion method, which is cross multiplying then dividing.

[IloveCupcakesandTea]

you sre a frikin life saver you are awsome i love you you explain in so much detail ....well sorry if i sound creepy but its just that its the day before csts and you helped me!!!! thanx

[KackassPR]

omg, not even my calculus professor explains so in detail, u have a gift of explanation thanks

[contida2003]

coul you please check this out?

i think 2% is not .002 but .02.

let me know

[TheLordsNerd]

Although your question is technically valid, it makes no sense in the context of this video.  his problem was dealing with .2% not 2%. Note the decimal point.

[Winsunn307]

Please come teach at my school.

[xralstinx]

Thanks so much for the help, very easy to understand!

[Squeaky4CC]

i have nock exams next week ima keep watching these till tues

[vickiormindyb]

Eddy, the Network Administrator where I work, told me the first thing to do when solving percentages is move the decimal point two places to the left.

I noticed you do that only after he told me that.

I asked him why he's going to our party as Count Dracula if he's so smart; I was joking of course.

"I'm NOT Dracula, I'm the vampire Le Stat from 'Interview With The Vampire.' "

"And vampires live forever," he said looking smug.

It was ghoulish appearance w/ his vampire teeth. XDD

[floridianmath]

thank you thank you it's very helping me thank you it's free class woohoo1

[BECKSIEnDAVIKANZ4EVA]

thank you very much for the help!.=D

[randompurple35]

he's just so easy to understand

[chulacharra]

Thanks your easy to learn from, I have found that there are certin people I can learn from ..Very percise.

[cholode805]

He is vary good, Thank you

[madmonkeynat]

Nice :)

[CaptainMomochan]

Thanks! =D

[Olivepersophone]

i freakin love this guy, he is funny!

[KarlNemetski]

cool beans

[up4itgal]

Great vid! Thanks for posting.

[herkysnerk]

THANK YOU.PLEASE KEEP POSTING.