Using a calculator

Many calculators have a % key. However, if you can't remember how to use the percent key, of if your calculator doesn't have one, you can turn the percent into a decimal and continue from there.

When you write a percent as a decimal, you first have to imagine there is a decimal point at the end of the percent number. Then you have to move this decimal point two places to the LEFT.

• 10% becomes .10 as a decimal (think of 10% as 10. %)

• 25% becomes .25 as a decimal (think of 25% as 25. %)

• 16% becomes .16 as a decimal (think of 16% as 16. %)

If you want to use a calculator to find 10% of $250, enter 250 on the keypad. Then enter * (for 'multiply by') or X if that is the key your calculator uses for 'multiply by.' Then enter .10 (Don't forget the decimal point that comes before the ten.) Press =, and if you've done this right, you'll get 25 as the answer. $25 is 10% of $250.

Try it again, but this time, find out what 25% of $250 is. First, enter 250 on the calculator. Then multiply this by .25 (and don't forget the decimal).

If you did it right, you got 62.5 as the answer.

If you write 62.5 with the dollar sign, it doesn't look quite right - $62.5. We need one more digit in the cents position. We don't have $62 and 5 cents, we have $62 and 50 cents - or $62.50. When we write amounts of money, we need two digits for cents, even if the digits are zero.