First, let’s go over what a fraction represents. The number above the line is called the numerator, while the number below the line is called the denominator. The fraction shows how many portions of the number there are, in relation to how many would make up the whole. For instance, in the fraction 40/81, we could say that the value is 40 portions, out of a possible 81 portions to make up the whole.
For percentages, the difference is that we want to know how many portions there are if there are 100 portions possible. “Percent” means “per hundred”. For example, if we look at the percentage 25%, that means we have 25 portions of the possible 100 portions. Re-writing this in fraction form, we see 25/100.
The first step in converting a fraction to a percentage is to adjust the fraction so that the denominator is 100. To do this, you first divide 100 by the denominator:
We can then adjust the whole fraction using this number, like so:
Reading this as a fraction, we can say that we have 49.2 portions of a possible 100 portions.
Re-writing this as a percentage, we can see that 40/81 as a percentage is 49.