# How do I find a percentage of something?April 27, 2020 11:31 AM   Subscribe

I failed basic maths back in the day

Let's say I have 15 items which would be 100%

But today I only got 4 of those 15 items done. What steps do I do on my calculator to find out what percentage I got done?
posted by fantasticness to Education (14 answers total) 5 users marked this as a favorite

The way I learned to simplify it is that percentage just means "Out of 100" so you can turn that into a fraction. And the number you don't know is X. And "is" is the same as equals.

So your situation is four out of fifteen is what percentage?

So 4/15 = X/100

Multiply both sides by 100

400/15 = X

posted by jessamyn at 11:36 AM on April 27, 2020 [8 favorites]

100/15=a

So, 26.66666666% percent.

As something of a math dingdong myself, I can only figure it out if I think of it like fractions. 4/15 = a/100, solve for a.
posted by Grandysaur at 11:36 AM on April 27, 2020 [1 favorite]

Write the amount you competed, out of the total number, like a test score or a fraction.
4/15. (you can imagine that line as horizontal or as a slash, they're the same)

Fun fact: that fraction line is the same as ÷, the division symbol with the two dots ...
those two dots represent the numbers on either side of the fraction line! So,

4/15
means
4 divided by 15

Type into a calculator and it spits out
= 0.266666
which rounds to 27%

Check your math by finding a similar fraction that you already know:
for instance, knowing that 4 out of 16 would be would be one-fourth, or 25%.
So 4 out of 15 should yield something similar.
posted by nouvelle-personne at 11:36 AM on April 27, 2020 [7 favorites]

I ask the Google: 4 is what percent of 15? Sometimes it just hands you the answer, other times it links to a percentage calculator. I like this one.
posted by Serene Empress Dork at 11:43 AM on April 27, 2020 [1 favorite]

Oh dear God. I can't calculate this either, so I just use Percentage Calculator.

In this case you would enter 4 and 15 into the values for X is what percentage of Y, click CALCULATE and get the answer 26.66
posted by DarlingBri at 11:45 AM on April 27, 2020 [3 favorites]

The way my kids teacher taught them was to say "out of" and then replace the out of with "over" So, 4 out of 15 which is 4 over 15 which is 4/15 which is 26.6%.
posted by AugustWest at 11:49 AM on April 27, 2020

Word problem time!

"4 of those 15"

4 of 15

4 divided by 15
posted by Revvy at 11:50 AM on April 27, 2020 [4 favorites]

Divide the # items complete by the total # of items. So 4/15. What this does is converts to a fraction which the proportion "# items complete per 1 item". So you completed 0.26667 items for every 1 on the list. To get a percentage, you want the "# of items complete per 100 items" -- which is literally multiply your first result by 100. So 4/15*100 gives you the percentage -- i.e., you completed 27% of your list, which really means you completed 27 items for every 100 items on your list.
posted by DoubleLune at 11:50 AM on April 27, 2020 [1 favorite]

What steps do I do on my calculator to find out what percentage I got done?

You got 4 out of 15 items done, so you want to divide 4 by 15.

4️⃣➗1️⃣5️⃣=
That gives you the number as a decimal-
`0.266666666666667`
or similar.
To get it as a percentage, multiply it by 100.
✖️1️⃣0️⃣0️⃣ =
`26.66666666666667`

posted by zamboni at 11:51 AM on April 27, 2020 [1 favorite]

100 divided by 15 then the answer times 4 .

I was also bad at math but I love shopping sales :-)
posted by pairofshades at 12:03 PM on April 27, 2020 [2 favorites]

I used to tell students that a fraction is a division problem waiting to happen.

To get a decimal, just do the division problem.

To get a percent, multiply the decimal by 100.
posted by wittgenstein at 12:34 PM on April 27, 2020 [2 favorites]

IS over OF

What percentage IS 50 OF 100.

50/100 = .5

To express that with the % symbol, multiply by 100.
posted by humboldt32 at 12:48 PM on April 27, 2020

I always remember it is “part divided by the whole.” 4 divided by 15.
posted by amanda at 12:55 PM on April 27, 2020

Lots of good stuff here, but I cannot resist trying to help.

Remember these things:

1. Fractions exist, and you already know what fraction of your total work you had done. You need to do 15. You did 4. So you did 4 of 15, which can be said as a fraction by putting 4 over 15. When we type, we say that like this:

4/15

2. Percentages are just another way of expressing a fraction, using 100 as the bottom number. 25/100 is 25%. 50/100 is 50%.

3. All fractions can be converted to a decimal version by dividing the top number by the bottom number. Sometimes, this is a nice, neat operation -- say, if you had 12 to do, and you did 3. 3 divided by 12 is . . . 0.25, which we also recognize as 25 out of 100, and thus as 25%.

4. So you can take your 4 out of 15 and do the same math: 4/15 = 0.2666666.... , which can be expressed as about 27%.

HTH!
posted by uberchet at 3:34 PM on April 27, 2020 [2 favorites]

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