Section C Section C Checkpoint

Problem 1

Find the value of $7 \times 60$ . Explain or show your reasoning.

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Solution

420. Sample response: 60 is 6 tens and $7 \times 6$ is 42 so $7 \times 60$ is 42 tens, and that's 420.

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Sample Response

420. Sample response: 60 is 6 tens and $7 \times 6$ is 42 so $7 \times 60$ is 42 tens, and that's 420.

Explain or show how each diagram represents $4 \times 13$ .

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Solution

Sample responses:

There are 4 rows or groups of squares and there are 13 in each row so altogether there are $4 \times 13$ squares.
The diagram shows that I can add the products $4 \times 10$ and $4 \times 3$ to find the value of $4 \times 13$ .

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Sample Response

Sample responses:

There are 4 rows or groups of squares and there are 13 in each row so altogether there are $4 \times 13$ squares.
The diagram shows that I can add the products $4 \times 10$ and $4 \times 3$ to find the value of $4 \times 13$ .

Andre’s book has 192 pages. He reads 15 pages each day for 5 days. How many pages does he still have to read to finish the book?

Write an equation to represent the situation. Use a letter for the unknown quantity.
Solve the problem. Explain or show your reasoning.

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Solution

Sample response: $192 - (5 \times 15) = p$ . $p$ is the number of pages Andre still needs to read.
117 pages. Sample response: $5 \times 10 = 50$ , $5 \times 5 = 25$ , so $5 \times 15 = 75$ . $192-70 = 122$ and $122 - 5 = 117$ , so $192-75=117$ . There are 117 pages left to read.

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Sample Response

Sample response: $192 - (5 \times 15) = p$ . $p$ is the number of pages Andre still needs to read.
117 pages. Sample response: $5 \times 10 = 50$ , $5 \times 5 = 25$ , so $5 \times 15 = 75$ . $192-70 = 122$ and $122 - 5 = 117$ , so $192-75=117$ . There are 117 pages left to read.