# How to Increase a Number by a Percentage ••• seb_ra/iStock/Getty Images

Math problems often require you to increase a number by a percentage. First, you find that percentage of the number, and then add it to the original number. The process is the same for all numbers and percents, and can be tweaked slightly to decrease a number by a percentage.

## Convert Percent to Decimal

The first step in increasing a number by a percentage is to convert the percent to a decimal. The easiest way to do this is move the decimal point two points to the left. For example, 30 percent as a decimal is 0.3, and 50 percent as a decimal is 0.5. If you have a calculator with a percent key (%), enter your number and press % to convert the percent to a decimal (you may have to press the = key on some models). Another way to work out the decimal is to remember that 100 percent is 1, because it is the whole of something. This means 50 percent is one-half (0.5), 25 percent is one-quarter (0.25), 75 percent is three-quarters (0.75) and so on.

## Work out Increase

Say you want to increase the number 10 by 50 percent. After you convert 50 percent to 0.5, work out 50 percent of 10 by multiplying 10 by 0.5. The answer is 5. On a calculator with a % key, you can type 10 × 50 % = to get the same answer.