How to Express a Fraction As a Decimal or Percent - dummies

How to Express a Fraction As a Decimal or Percent

By Angie Papple Johnston

Sometimes it’s easier to work with a fraction by expressing it as a decimal or a percent. If you run into a question like this on the ASVAB Arithmetic Reasoning subtest, the following info will help make these conversions a snap!

Here’s how to convert between forms:

  • To change a fraction into a decimal: Divide the numerator (top number) by the denominator (bottom number). Given that handy explanation, 3/5 (or 3 ÷ 5) converted into decimal form is 0.6.

Some fractions convert to repeating decimals—a decimal in which one digit is repeated infinitely. For instance, 2/3 is the same as 0.66666… (with the sixes never stopping).

Repeating decimals are often rounded to the nearest hundredth; therefore, 2/3 rounds to 0.67. (Remember: The first space to the right of the decimal is the tenths place, the second space is the hundredths place, and the third is the thousandths, and so on.)

  • To make a decimal into a percent: Move the decimal point two spaces to the right and add a percent sign. For example, 0.6 becomes 60%.

Practice question

  1. The population of Grand Island, Nebraska, grew by 600,000 people between 1995 and 2005, one-fifth more than the town council predicted. The town council originally predicted the city’s population would grow by

A. 400,000

B. 500,000

C. 300,000

D. 100,000

Answer and explanation

  1. The correct answer choice is B.

Let x equal the original number of how much Grand Island would grow. An additional 1/5 would make the population growth 6/5 of x:

6 ÷ 5 = 1.2

So, you can express the equation as 1.2x = 600,000. To solve for x, divide both sides of the equation by 1.2, which gives you x = 500,000.