percentage calculator

What is percentage

What is percentage? Percentage is a way to express a relation between two numbers as a fraction of 100. In other words, the percentage tells us how one number relates to another. If we know that number A is 25% of number B, we know that A to B is like 25 is to 100 (one more transformation: A is four times smaller than B). This is Percentage Calculator's lesson on what is percentage.

It's easiest to explain what is percentage on cookies. It is surprising how often cookies save the day, right? Say we have a big drawer with 100 compartments (a 10x10 grid). Every compartment is 1 hundredth, or 1% of the whole drawer. We then fill this drawer with cookies in a way that gives us exactly the same number of cookies in each compartment.

At first, let's start with 100 cookies. It's easy: every compartment gets exactly 1 cookie. So one percent of one hundred is one.

Let's go with something a bit harder and four times more delicious: 400 cookies! We're dividing them evenly and every compartment gets 4 cookies. Cookies look smaller, but in our imagination they are the the same, just the drawer is much bigger! One percent of 400 is 4. How about 15 percent? It's 15 compartments times 4 cookies - 60 cookies. My tummy starts to ache a little, but it has never stopped me from eating more cookies!

Now something even harder - 250 cookies. Oh-oh... we divided up the first 200 cookies, placing 2 in every compartment. Now we are left with 50 cookies that need to be spread evenly... hmmm... it's half a cookie in every box. You are right - this time 1 percent of the total number of cookies is two and a half. How many do we have in 15 boxes? 2.5 * 15 is 37.5.

So what is percentage good for? As I wrote in the first paragraph, percentage is a way to express a ratio. Say you are taking a graded exam. If I told you that you got 123 points, it really would not tell you anything. 123 out of what? Now, if I told you that you got 82%, it's a solid information. Even if I told you you got 123 out of 150, it's harder to feel how well you did. A week earlier there was another exam and you scored 195 of 250, or 78%. While it's hard to compare 128 of 150 to 195 of 250, it's easy to tell that 82% score is better than 78%. After all, it's the percentage that counts!

Percentages can easily be converted to decimals. Just divide the percentage by 100 and you are set. 15% is the same as 0.15. 0.15 of 250 cookies is thirty seven and a half.

OK. Now that we know what is percentage, let's try to learn calculating it. You could use our percentage calculator to easily and quickly calculate percentages, but it's always better to be able to to it on your own, right? If you agree, read the how to calculate percentage page. Also, it's cool to know how to calculate percentage increase and percentage decrease.