Calculators allow you to work out percentages. Whether or not your calculator has a percentage button, the process is incredibly simple. If your calculator has a percentage key, you can use the desired percent directly; if your calculator doesn’t have a percentage key, you divide the percentage amount by 100 to get the correct numerical value.
TL;DR (Too Long; Didn't Read)
To calculate half a percent on a calculator, you multiply the whole value by 0.5 followed by the % button. If your calculator doesn't have a percentage button, you multiply the whole value by 0.005, which is the numerical value of half a percent.
What Is Percentage
A percentage is a portion of a whole number, where 100 percent is the whole amount. In other words, percentage means "out of one hundred." Percentages can also be converted to fractions; for example, 100 percent is one, 75 percent is three-quarters, 50 percent is one-half and 25 percent is one-quarter. Imagine you have made a pie and split it into eight slices to share with your friends. One slice is one-eighth of the whole pie, which is 12.5 percent (100 ÷ 8). If three slices are eaten, this means five slices are left. You can work out what percentage of the pie is left by converting five-eighths to a percentage. The answer is 62.5 percent: (100 ÷ 8) × 5 or (5 ÷ 8) × 100.
Calculating Half a Percent
Numerically, 100 percent is 1, so you divide the percentage value by 100 to get its numerical value. For example, 25 percent is 0.25 (25 ÷ 100), 50 percent is 0.5 (50 ÷ 100), 75 percent is 0.75 (75 ÷ 100) and so on. If a math problem requires you to work out half a percent of something, the equation 0.5 ÷ 100 converts this to its numerical value of 0.005.
Working out Percentages on Calculators
On a very basic calculator without a percentage button (%), you work out half a percent of something using the multiply (×) and equals (=) buttons. For example, to work out half a percent of 240, type 240 into the calculator. Then press the multiply button, followed by 0.005 (the numerical value of half a percent) and then the equals button: 240 × 0.005 = 1.2. So, half a percent of 240 is 1.2.
To work out the same equation on a calculator with a percentage button, type 240 × 0.5 % = to get the same answer: 1.2. On some calculators, you don't need to press the equals button.
A more advanced math problem might ask you to work out how half a percent affects a value. For example, if a $200 pair of shoes are reduced by half a percent, what is the sale price? The calculation is 200 × 0.5 % = 1. This means the shoes are reduced by $1, so the sale price is $199 ($200 - $1).