4-8 Number Sense to Place Decimal

4-8 Number Sense to Place Decimal

by Haley Hanson

​Use number sense to decide where the decimal point belongs in the product. Tell the place.

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1) 5 x 3.4 = 17

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​2) 3.1 x 6.2 = 1922

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​3) 0.6 x 0.4 = 24

Multiple Choice

Place the decimal in the product.

5.01 x 3 = 1503

• 1.503

• 15.03

• 0.1503

• 150.3

Multiple Choice

Place the decimal in the product.

6.22 x 3 = 1866

• 1.866

• 186.6

• 18.66

• 0.1866

Multiple Choice

Place the decimal in the product.

0.9 x 0.9 = 81

• 0.81

• 8.1

• 81.0

Multiple Choice

Place the decimal in the product.

1.8 x 1.9 =342

• 34.2

• 0.342

• 3.42

​Tell whether or not the decimal point has been placed correctly in the product. If not, rewrite the product with the decimal point correctly placed.

​1) 12 x 4.8 = 57.6

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​2) 5.2 x 6.4 = 3.328

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​3) 6.99 x 21 = 14.679

Fill in the Blanks

​Tell whether or not the decimal point has been placed correctly in the product. If not, rewrite the product with the decimal point correctly placed.

0.05 x 12.4 = 6.2

Fill in the Blanks

​Tell whether or not the decimal point has been placed correctly in the product. If not, rewrite the product with the decimal point correctly placed.

18 x 3.38 = 60.84

Fill in the Blanks

​Tell whether or not the decimal point has been placed correctly in the product. If not, rewrite the product with the decimal point correctly placed.

9.01 x 91 = 81.991

Multiple Choice

Describe the unknown factor.

______ x 5.1 is about 300

• the unknown factor would need to be a decimal close to 600

• the unknown factor would need to be a decimal close to 60

• the unknown factor would need to be a decimal close to 6

Multiple Choice

Janelle wrote 23.4 for the product of 7.8 x 0.3. Use number sense to decide if Janelle placed the decimal point in the correct place in the product. If it is incorrect, give the correct product.

• Janelle is correct

• Janelle is incorrect; the product should be 2.34

• Janelle is incorrect; the product should be 0.234

• Janelle is incorrect; the product should be 234.0

Multiple Choice

Which of the following is the missing factor?

_____ x 2.3 = 34.73

• 0.151

• 1.51

• 15.1

• 151

Multiple Choice

CHALLENGE***

Which two factors would give a product of 7.5?

• 0.3 x 0.25

• 0.3 x 2.5

• 3 x 0.25

• 3 x 2.5