Percents and decimals are very similar forms, so everything you know about decimals carries over when you're working with percents. All you need to do is convert your percent to a decimal, and you're good to go.
To change a whole-number percent to a decimal, simply replace the percent sign with a decimal point and then move this decimal point two places to the left; after this, you can drop any trailing zeros. Here are a few common conversions between percents and decimals:
| 100% = 1 | 75% = 0.75 | 50% = 0.5 |
| 25% = 0.25 | 20% = 0.2 | 10% = 0.1 |
Sometimes a percent already has a decimal point. In this case, just drop the percent sign and move the decimal point two places to the left. For instance, 12.5% = 0.125.
Sample questions
Change 80% to a decimal.
0.8. Replace the percent sign with a decimal point — changing 80% to 80 — and then move the decimal point two places to the left:
80% = 0.80
At the end, you can drop the trailing zero to get 0.8.
Change 37.5% to a decimal.
0.375. Drop the percent sign and move the decimal point two places to the left:
37.5% = 0.375
Practice questions
Change 90% to a decimal.
A common interest rate on an investment such as a bond is 4%. Convert 4% to a decimal.
Find the decimal equivalent of 99.44%.
What is 243.1% expressed as a decimal?
Following are answers to the practice questions:
0.9. Replace the percent sign with a decimal point and then move this decimal point two places to the left:
90% = 0.90
At the end, drop the trailing zero to get 0.9.
0.04. Replace the percent sign with a decimal point and then move this decimal point two places to the left:
4% = 0.04
0.9944. Drop the percent sign and move the decimal point two places to the left:
99.44% = 0.9944
2.431. Drop the percent sign and move the decimal point two places to the left:
243.1% = 2.431