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**Multiply and Divide Decimals**

Chapter 6

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**Lesson 1 – Estimate Products of Whole Numbers and Decimals**

Round to the ones place. Example: Estimate x 5 15.8 → 16 x 5 → x 5 80

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**Lesson 3 – Multiply Decimals by Whole Numbers**

When multiplying a decimal by a whole number, place the decimal point in your answer directly below where it is in the problem. Examples – 1.) 2 × ) 12 × × × 0.7

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**Lesson 5 – Multiply Decimals**

When multiplying a decimal by a decimal, move the decimal points all the way to the right to make it a whole number. In your answer, move the decimal point the same number of places to the left. decimal places x x decimal place decimal places = – move decimal point 3 places to the left. *If there are no more numbers on the left, you must add zeros.

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**Lesson 8 – Multiplication Properties**

Commutative Property of Multiplication The order in which the factors are multiplied does not change the product. Ex. – 5 x 4 = 4 x 5 Associative Property of Multiplication The way in which the numbers are grouped does not change the product. Ex. – (7 x 3) x 9 = 7 x (3 x 9) Identity Property of Multiplication The product of any number and 1 equals the number. Ex x 1 = 12

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**Lesson 9 – Estimate Quotients**

Use compatible numbers to divide. Remember, the numbers must go in evenly – no remainders! Example: $17.50 ÷ 7 → $ 18 ÷ 7 *Does not go in evenly – pick different numbers $21 ÷ 7 = $ or ÷ 7 = 2

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**Lesson 11 – Divide Decimals by Whole Numbers**

You DO NOT need to use models. The steps are simple. Write the decimal point in your answer DIRECTLY ABOVE where it is in the problem. ↓ __.__ 3) 4.2 Divide as you would divide a whole number. _1.4__ -3 ↓ 12 -12

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**Lesson 13 – Divide Decimals**

Move the decimal point in the divisor to make it a whole number. Move the decimal point in the dividend the same number of places. Place the decimal point and divide. _____ ______ o.05) → o05.) 420.5 ↑ 2 places ↑ _ to the right 5) 420.5 -40↓ 20 -20↓ 05 - 05

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