Calculating percentages is a fairly simple area of mathematics due to the way that it always works in

hundreds.

If you have a scientific calculator, you should find a percentage calculation button on it along with the

other functions. To find a percentage, you simply need to enter the whole number, then press the

addition key, enter your desired percentage, and press the percentage function key. Like so:

500 + 50 '%' (calculator displays 250)

The calculator will then show you the percentage figure, and if you press the 'equals' key, it will add it to the whole number, which in this example will make 750.

If you don't have a scientific calculator to hand but still have a simple one (you can find these on almost every cell phone from the last several years), the process becomes only slightly more complex. You will need to first enter the whole number, then divide it by 100 to find one percent of it, and then multiply that figure by your desired percentage.

500 / 100 = 5, 5 * 50 = 250 (where '/' denotes division and '*' denotes multiplication)

Once you have the resulting figure, you can use it in whichever calculation you want to - adding or subtracting it from the initial number etc.

For the reverse, in other words to find out what one number is as a percentage of another, you just need to divide the first number by the second. For example, to find out what percentage 200 is of 500, you just divide 200 by 500.

200 / 500 = 0.4

0.4 expressed as a percentage is 40per cent. It works the same with the numbers reversed - 500 is 250per cent percent of 200. As the first number is greater, the end result will always be over 100per cent.