Lesson 15

Adding and Subtracting Decimals

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Problem 1

For each subtraction problem, circle the correct calculation.

  1. \(7.2 - 3.67\)
  2. \(16 - 1.4\)
Option a and option b, three decimal subtraction problems for each option. 

Solution

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Problem 2

Explain how you could find the difference of 1 and 0.1978.

Solution

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Problem 3

A bag of chocolates is labeled to contain 0.384 pound of chocolates. The actual weight of the chocolates is 0.3798 pound.

  1. Are the chocolates heavier or lighter than the weight stated on the label? Explain how you know.

  2. How much heavier or lighter are the chocolates than stated on the label? Show your reasoning.

Solution

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Problem 4

Complete the calculations so that each shows the correct sum.

3 calculations with missing digits, a, b, and c. 

Solution

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Problem 5

A shipping company is loading cube-shaped crates into a larger cube-shaped container. The smaller cubes have side lengths of \(2\frac12\) feet, and the larger shipping container has side lengths of 10 feet. How many crates will fit in the large shipping container? Explain your reasoning.

Solution

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(From Unit 3, Lesson 10.)

Problem 6

For every 9 customers, the chef prepares 2 loaves of bread.

  1. Here is double number line showing varying numbers of customers and the loaves prepared. Complete the missing information.

    Double number line, 5 evenly spaced tick marks. Top line, number of customers. Scale 0 to blank, by 9’s. Bottom line, loaves of bread. Scale 0 to blank, by 2’s.

  2. The same information is shown on a table. Complete the missing information.

customers loaves
9 2
4
27
14
1


c. Use either representation to answer these questions.

  • How many loaves are needed for 63 customers?
  • How many customers are there if the chef prepares 20 loaves?
  • How much of a loaf is prepared for each customer?

Solution

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(From Unit 2, Lesson 9.)