# how to calculate percentage

A percentage is a way of expressing a number as a fraction of 100.

For example, 30% is the same thing as saying 30/100.

The best-known usage of percentages is in describing how large one quantity

is when compared with another quantity, such as “30% bigger”

or “20% greater”.

In mathematics, it is seen that if three numbers  a, b and c are in proportion then:  a = bc / 100.  Thus for percent values we just need to know the value of ‘b’ and we can calculate the other two values: Percent= Value / Base x 100 .

To calculate the percentage of a number, multiply that number by the percentage value.

For example, to find 45% of 80:  multiply 80 by 45%, which is 36.  So 45% of 80 is 36.

Most calculators have a button that says “percent” or “%” for short. Pressing percent gives you your answer in percentage form instead of decimal format, so this works well if you already know the answer is a percentage and you just want to change it into an easier-to-understand format. If you don’t know what the answer should be in percentage form, though, it’s no problem; you can enter the original number and then your desired percentage (both in decimal form), and press the percent button to get the answer.

To calculate what 45% of 80 is, do this:

1) Put the original number (80) into calculator memory.

2) Type “45%” on calculator keypad.

3) Press equals (or whatever your calculator’s percent button is called).

The answer, 36, will show up on the screen.

Another example: what is 25% of 16?

1) Put 16 into memory. 