top

Chapter 4—Decimals

4-6 Multiplying Decimals

 When you complete the work for this section, you should be able to: Demonstrate an ability to multiply decimal numbers without making errors.

The procedures for multiplying decimal fractions is almost the same as multiplying whole numbers. The only difference is that we have to deal with the decimal points in the decimal-fraction versions—but not until the final step.

 Procedure Step 1: Write the decimal values in vertical form, aligning the right-hand digits in the factors. Note: Align the right-hand digits, and not the decimal points as in decimal addition and subtraction. Step 2: Perform the multiplication operation without paying any attention to the decimal points. Step 3: Count the total number of digits to the right of the decimal points in the factors. Count that many places to the left in the product, and place the decimal point there.

Example 1

 Problem 1.2 x 6 = _____ Procedure Write the decimal values in vertical form, aligning the right-hand digits in the factors. 1.2 x    6 Perform the multiplication operation without paying any attention to the decimal points. 1.2 x    6    72 Count the total number of digits to the right of the decimal points in the factors. Count that many places to the left in the product, and place the decimal point there. 1.2 x    6   7.2 Solution 1.2 x 6 = 7.2

Example 2

 Problem 45.3 x 1.68 = _____ Procedure Write the decimal values in vertical form, aligning the right-hand digits in the factors. 45.3 x 1.68 Perform the multiplication operation without paying any attention to the decimal points. 45.3 x    1.68     3624   2718 453       76104 Place the decimal point. 45.3 x    1.68     3 624   27 18 45 3       76.104 Solution 45.3 x 1.68 = 76.104

Examples and Exercises

 Multiplying Decimals Use these interactive examples and exercises to strengthen your understanding and build your skills: