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# Percent of a whole number

Discover how to calculate percentages with a simple example: finding 30% of 6. Learn two methods, using fractions and decimals, to solve this problem. Both approaches lead to the same result, showing that 30% of 6 equals 1.8. Master these techniques for everyday calculations. Created by Sal Khan.

## Want to join the conversation?

- At0:55, how do you turn the improper fraction into a mixed number?(7 votes)
- you can turn an improper fraction to a mixed number by dividing the top number by the bottom number and that is how you do it :)(40 votes)

- I don't understand how Sal turned the fraction into a decimal. How is 4/5 related to 4 divided by 5? (At1:00)(13 votes)
- The slash in between the 4 and the 5 means division. All fractions are division sentences written in a different form. To convert a fraction to a decimal, you divide the numerator by the denominator. For 4/5, you divide 4 by 5 to get 0.8(27 votes)

- Why make these things so complex? I will just divide 6 by 100. And then multiply by 30.

6/100=0.06

0.06*30=1.8

simple as that.(12 votes)- Sal is showing different approaches that can be used for this problem. Pick one that works for you.

Note: While your method works, you do have a process error. Technically, you treated the problem as 6% * 30 when the problem is 30% * 6 = 30/100 * 6 = 0.3 * 6 = 1.8(14 votes)

- at a scale of 500 percent a measurment is 165mm. what is the actual size?(10 votes)
- The video teaches how to find a percentage of a number, here you're given the percentage and looking for the original number, so you should reverse the operation, and do division.

What is the number when multiplied by 500/100 (that's 500%) gives 165?

? x 500/100 = 165

You can divide 165 by 500/100 to find the answer, or since we're dividing by a fraction, you can just multiply by its reverse, so it becomes likes this:

165 x 100/500 = ?

(165 x 100) / 500 = 16500 / 500

16500 / 500 = 33

The original number should be 33.(12 votes)

- The video teaches how to find a percentage of a number, here you're given the percentage and looking for the original number, so you should reverse the operation, and do division.

What is the number when multiplied by 500/100 (that's 500%) gives 165?

? x 500/100 = 165

You can divide 165 by 500/100 to find the answer, or since we're dividing by a fraction, you can just multiply by its reverse, so it becomes likes this:

165 x 100/500 = ?

165 x 100 = 16500

16500 / 500 = 33

The original number should be 33.

It will help you to understand...if you could then hit a like 👍🏻👍🏻(12 votes) - this is too quick can someone explain it to me?(6 votes)
- So basically 50% of 100 is 50, and 50% of 5 is 2.5, if you get fractions and decimals then this is easy.

Here is a method to make calculating percentages easier.**Graph paper or any paper recommended**

Let's say I want to find 80% of 200, then I would write 200 x 80 (over 100)= ?. The two 0s from the 80 over 100 and 200 cancel out each other. 80 * 2= 160, so 160 is 80% of 200.

Hope this helps(11 votes)

- Can you explain it better Sal other then that Khan Academy is awsome(6 votes)
- Multiply the whole number by 100. The resulting answer is its value as a percentage. Another way is to add a decimal point after the whole number such as 4, and then move the decimal two spaces to the right, fill in each of those empty spaces with a zero, and add a percentage symbol = 400%.(7 votes)

- Sal drawing a dot instead of a multiplication symbol doesn't help my confusion...(4 votes)
- The "." is used instead of "x" since in algebra "x" is a variable and isn't used for multiplication, you will realize later in you math journey it is way better to use a "." rather than an "x"(10 votes)

- I found an easier way to calculate a percent of a whole number.

So 40% of 6 is 2.4

How do we find that?

add a zero to 6 to make it 60 (this is the easier way)

and multiply 6 times 4 to get 24

Now we shift the decimal point to the right and it becomes 2.4.

If you are struggling with that way, you could just find 10% of the number (which is 0.6 in that case) and multiply it by 4.(3 votes) - At0:17, how does multiplying 30/100 (or 3/10) by 6 (or 6/1,) equal 30% of 6?

Or 0.3 (or 0.30) by 6 equal 30% of 6?(3 votes)- Pay attention to the whole video or try the arithmetic course and see if that helps.(3 votes)

## Video transcript

Let's see if we can figure
out what 30% of 6 is. So one way of thinking
about 30%-- this literally means 30 per 100. So you could view
this as 30/100 times 6 is the same thing as 30% of 6. Or you could view this
as 30 hundredths times 6, so 0.30 times 6. Now we could solve
both of these, and you'll see that we'll
get the same answer. If you do this multiplication
right over here, 30/100-- and you
could view this times 6/1-- this is equal to 180/100. And let's see. We can simplify. We can divide the numerator
and the denominator by 10. And then we can divide the
numerator and the denominator by 2. And we will get 9/5, which is
the same thing as 1 and 4/5. And then if we wanted to write
this as a decimal, 4/5 is 0.8. And if you want to
verify that, you could verify that
5 goes into 4-- and there's going
to be a decimal. So let's throw some
decimals in there. It goes into 4 zero times. So we don't have to
worry about that. It goes into 40 eight times. 8 times 5 is 40. Subtract. You have no remainder, and
you just have 0's left here. So 4/5 is 0.8. You've got the 1 there. This is the same
thing as 1.8, which you would have gotten
if you divided 5 into 9. You would've gotten 1.8. So 30% of 6 is equal to 1.8. And we can verify it
doing this way as well. So if we were to multiply
0.30 times 6-- let's do that. And I could just write that
literally as 0.3 times 6. Well, 3 times 6 is 18. I have only one digit
behind the decimal amongst both of these
numbers that I'm multiplying. I only have the 3 to the
right of the decimal. So I'm only going
to have one number to the right of
the decimal here. So I just count one number. It's going to be 1.8. So either way you think about
it or calculate it, 30% of 6 is 1.8.