| 3/8 is 3 ÷ 8 = 0.375 |
|
| 1/4 is 1 ÷ 4 = 0.25 |
|
As discussed earlier, to convert from a percent to a decimal, simply move the decimal point two spots to the left and remove the percent symbol:
53% becomes 0.53
40.57% becomes 0.4057
3% becomes 0.03
To convert from a percent to a fraction, remember that per cent literally means “per hundred,” so put the percent figure over one hundred and then simplify:
45% becomes 45/100 = 9/20
8% becomes 8/100 = 2/25
Change 87% to a decimal.
Change 30% to a fraction.
To convert from a decimal to a percent, simply move the decimal point two spots to the right and add a percent symbol:
0.53 becomes 53%
0.4057 becomes 40.57%
0.03 becomes 3%
To convert from decimal to fraction, it helps to remember the proper names for the digits: the first digit to the right of the decimal point is the tenths digit, next is the hundredth-digit, next is the thousandth-digit, and so on.
| 4 | 5 | 7 | • |
1 | 2 | 3 | 5 |
| Hundreds | Tens | Units | Tenths | Hundredths | Thousandths | Ten-Thousandths |
The number of zeroes in the denominator should match the number of digits in the decimal (not including a possible 0 in front of the decimal point). For example:
0.3 is three-tenths, or 3/10
0.23 is twenty-three hundredths, or 23/100
0.007 is seven-thousandths, or 7/1,000
Change 0.37 to a percent.
Change 0.25 to a fraction.
To convert from a fraction to a decimal, divide the numerator by the denominator:
| 3/8 is 3 ÷ 8 = 0.375 |
|
| 1/4 is 1 ÷ 4 = 0.25 |
|
To convert from a fraction to a percent, first convert from fraction to decimal, and then convert that decimal to a percent.
Step 1: 1/2 = 1 ÷ 2 = 0.50
Step 2: 0.50 = 50%
Dividing the numerator by the denominator can be cumbersome and time consuming. Ideally, you should have the most basic conversions memorized before test day. A list of common FDP conversions that you should memorize appears later in the chapter.
The following chart reviews the ways to convert from fractions to decimals, from decimals to fractions, from fractions to percents, from percents to fractions, from decimals to percents, and from percents to decimals. You should practice so that each becomes natural to you.
|
Fraction
|
Decimal 0.375 | Percent 37.5% |
Fraction
|
Divide the numerator by the denominator: 3 ÷ 8 = 0.375 |
Divide the numerator by the denominator and move the decimal two places to the right, adding a percent symbol: 3 ÷ 8 = 0.375 → 37.5% |
|
| Decimal 0.375 |
Use the place value of the last digit in the decimal as the denominator, and put the decimal’s digits in the numerator. Then simplify: 
|
Move the decimal point two places to the right and add a percent symbol: 0.375 → 37.5% |
|
| Percent 37.5% |
Use the digits of the percent for the numerator and 100 for the denominator. Then simplify:
|
Move the decimal point two places to the left and remove the percent symbol: 37.5% → 0.375 |
Change
to a decimal.
Change
to a percent.