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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.

fig040501.gif (1241 bytes)

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.

fig040502.gif (1118 bytes)

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.

fig040503.gif (2764 bytes)

Example 1

Problem

1.2 x 6 = _____

Procedure
  1. Write the decimal values in vertical form, aligning the right-hand digits in the factors.

   1.2
x    6

  1. Perform the multiplication operation without paying any attention to the decimal points.
   1.2
x    6
   72
  1. 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
  1. Write the decimal values in vertical form, aligning the right-hand digits in the factors.

   45.3
x 1.68

  1. Perform the multiplication operation without paying any attention to the decimal points.
      45.3
x    1.68
    3624
  2718
453    
  76104
  1. 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:

David L. Heiserman, Editor

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All Rights Reserved

Revised: June 06, 2015