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# Decimals and Percents Study Guide for McGraw-Hill's ASVAB

By McGraw-Hill Professional
Updated on Mar 16, 2011

### Decimals

A decimal is a number with one or more digits to the right of the decimal point. 0.862 and 3.12 are decimals. (Note that a zero is shown to the left of the decimal point when the decimal is between 0 and 1.)

Working with Decimals   On the ASVAB, you'll probably need to know how to add, subtract, multiply, and divide decimals. You'll also need to know how to change decimals to fractions.

Adding and Subtracting Decimals To add or subtract decimals, line up the decimal points one above the other. Then add or subtract as you would normally. Place a decimal point in the answer beneath the other decimal points.

Examples (Addition)

Add zeros in the blank decimal places to make this problem easier to tackle.

Examples (Subtraction)

Multiplying Decimals To multiply decimals, follow the usual multiplication rules. Count the number of places to the right of the decimal point in each factor. Add the numbers of places. Put that many decimal places in the answer.

Examples

Dividing Decimals To divide decimals, follow the usual division rules. If the divisor (the number you are dividing by) has decimals, move the decimal point to the right as many places as necessary to make the divisor a whole number. Then move the decimal point of the dividend (the number you are dividing) that same number of places to the right. (You may have to add some zeros to the dividend to make this work.) Put the decimal point in the answer directly above the decimal point in the dividend.

Examples

Note that the decimal point is moved two places to the right in each term. The decimal point in the answer is directly above the decimal point in the dividend.

In this example, the decimal point is moved two places to the right in 1.25 to make 125. The dividend 50 can also be expressed as 50.00 (adding zeros), and moving the decimal point the same number of places to the right makes 5,000. No decimal point needs to be shown in the answer because the answer is a whole number.

Changing Decimals to Fractions Read the decimal and then write the fraction. Reduce the fraction to its lowest terms.

Examples

Changing Fractions to Decimals To change a fraction to a decimal, divide the numerator by the denominator.

Examples

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