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

  1. 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.

  2. 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

  1. Change 90% to a decimal.

  2. A common interest rate on an investment such as a bond is 4%. Convert 4% to a decimal.

  3. Find the decimal equivalent of 99.44%.

  4. What is 243.1% expressed as a decimal?

Following are answers to the practice questions:

  1. 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.

  2. 0.04. Replace the percent sign with a decimal point and then move this decimal point two places to the left:

    4% = 0.04

  3. 0.9944. Drop the percent sign and move the decimal point two places to the left:

    99.44% = 0.9944

  4. 2.431. Drop the percent sign and move the decimal point two places to the left:

    243.1% = 2.431