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Decimals Multiplication and Division Review

Learn to multiply and divide decimals, estimate quotients, and understand properties of multiplication. Practice with examples and additional problems. Enhance mental math skills to simplify calculations.

fredcarroll
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Decimals Multiplication and Division Review

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  1. Multiplying and Dividing Decimals Section 1-3 (Pages 17-22)

  2. Review… Estimate each quotient using compatible numbers. 1. 24.8 ÷ 4.9 2. 103.8 ÷ 13.2 3. 128.62 ÷ 9.86 4. 41.77 ÷ 6.07 About 5 About 8 About 13 About 7

  3. Properties of Multiplication Identity Property The product of 1 and “a” is “a”. 5 x 1 = 5 1 x 5 = 5 Zero Property The product of 0 and any number is 0. 5 x 0 = 0 0 x 5 = 0

  4. Properties of Multiplication Commutative Property Changing the order of factors does not change the product. 5 x 2 = 2 x 5 Associative Property Changing the grouping of factors does not change the product. (3 x 2) x 5 = 3 x (2 x 5)

  5. To multiply decimals… Step 1: Multiply as if the factors are whole numbers. Step 2: Add the number of the decimal places in both factors to find the number of decimal places in the product.

  6. Example Find the product of 0.2 x 0.7 Step 1: Multiply as with whole numbers. 2 x 7 14 Step 2: Locate the decimal point. 0.2 x 0.7 0.14 1 decimal place 1 decimal place 2 decimal places

  7. Example Find the product of 1.45 x 2.6. Step 1: Multiply as with whole numbers. Step 2: Locate the decimal point.

  8. Example Find the product of 1.02 x 3.6. Step 1: Multiply as with whole numbers. Step 2: Locate the decimal point.

  9. Multiplying using the Properties… Use mental math to find 2 x 4.097 x 0.5 We know that 2 x 0.5 will give us 1 and then the product of 1 and 4.097 is 4.097. 2 x 4.097 x 0.5 = 2 x 0.5 x 4.097 Commutative Property Associative Property = (2 x 0.5) x 4.097 = 1 x 4.097 Simplify = 4.097 Identity Property

  10. Example Use mental math to find the product of 1.09 x 23.6 x 0.

  11. Example Use mental math to find the product of 2.5 x 6.3 x 4.

  12. Additional Problems 1. 1.45 x 2.6 2. 1.3 x 0.005 3. 41 x 7.5 4. 0 x 2.78 x 1 5. 5 x (4.3 x 1)

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