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Published byKelley Reynolds Modified over 9 years ago

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Multiplying Decimals Multiplying decimals is similar to multiplying whole numbers. The difference is that we place a decimal point in the product. 7 10 3 100 21 1000 0.7 = = 1 decimal place 2 decimal places = 3 decimal places

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**Chapter 1 / Whole Numbers and Introduction to Algebra**

Multiplying Decimals Step 1: Multiply the decimals as though they were whole numbers. Step 2: The decimal point in the product is placed so the number of decimal places in the product is equal to the sum of the number of decimal places in the factors.

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Examples Multiply: × Multiply: ×

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Dividing by a Decimal Division of decimal numbers is similar to division of whole numbers. The only difference is the placement of a decimal point in the quotient. If the divisor is a whole number, divide as for whole numbers; then place the decimal point in the quotient directly above the decimal point in the dividend. 8 4 quotient divisor 63 52.92 dividend 2 5 2 -2 52

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Dividing by a Decimal If the divisor is not a whole number, we need to move the decimal point to the right until the divisor is a whole number before we divide. divisor 6 3 52 92 . dividend 63 529 2 . 8 4 63 52 9.2 - 504 25 2 -252

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**Chapter 1 / Whole Numbers and Introduction to Algebra**

Dividing by a Decimal Step 1: Move the decimal point in the divisor to the right until the divisor is a whole number. Step 2: Move the decimal point in the dividend to the right the same number of places as the decimal point was moved in Step 1. Step 3: Divide. Place the decimal point in the quotient directly over the moved decimal point in the dividend.

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**Examples Divide: 0.084 ÷ 0.35 Divide and round to two decimal places:**

÷ 0.032

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**Chapter 1 / Whole Numbers and Introduction to Algebra**

Estimating Operations on Decimals Estimating sums, differences, products, and quotients of decimal numbers is an important skill whether you use a calculator or perform decimal operations by hand.

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**Chapter 1 / Whole Numbers and Introduction to Algebra**

Estimating When Adding Decimals Add Exact Estimate rounds to rounds to This is a reasonable answer.

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**Chapter 1 / Whole Numbers and Introduction to Algebra**

Helpful Hint When rounding to check a calculation, you may want to round the numbers to a place value of your choosing so that your estimates are easy to compute mentally.

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**Chapter 1 / Whole Numbers and Introduction to Algebra**

Estimating when Multiplying Decimals Multiply 32.3 1.9. Exact Estimate rounds to rounds to This is a reasonable answer.

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**Chapter 1 / Whole Numbers and Introduction to Algebra**

Estimating When Dividing Decimals Divide ÷ 2.8 Exact Estimate rounds to This is a reasonable answer.

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**Examples Estimate, then evaluate: 44.612 × 2.14**

Divide. Round to two decimal places. 52 ÷ 18

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