Section A Section A Checkpoint

Problem 1

Find each sum or difference. If you get stuck, consider using a number line.
  1. 8+-118 + \text-11
  2. -1+10\text-1 + 10
  3. 12−(-6)12 - (\text-6)
  4. -4.5−2.3\text-4.5 - 2.3
  5. -79+29\text-\frac79 + \frac29
Show Solution
Solution
  1. -3
  2. 9
  3. 18
  4. -6.8
  5. -59\text-\frac59
Show Sample Response
Sample Response
  1. -3
  2. 9
  3. 18
  4. -6.8
  5. -59\text-\frac59

Problem 2

A librarian keeps track of how many books are checked in or out of the library during the day.

  • 3 books checked out
  • 6 books checked in
  • 2 books checked in
  • 5 books checked out
  • 1 book checked in
  • 4 books checked out
  1. How could the librarian use signed numbers to represent this information?
  2. How does the total number of books in the library at the end of the day compare to the beginning of the day?
Show Solution
Solution
  1. Sample response: The librarian could use positive numbers to represent books that get checked in and negative numbers to represent books that get checked out.
  2. There are 3 fewer books in the library at the end of the day, because -3+6+2+-5+1+-4=-3\text-3 + 6 + 2 + \text-5 + 1 + \text-4 = \text-3.
Show Sample Response
Sample Response
  1. Sample response: The librarian could use positive numbers to represent books that get checked in and negative numbers to represent books that get checked out.
  2. There are 3 fewer books in the library at the end of the day, because -3+6+2+-5+1+-4=-3\text-3 + 6 + 2 + \text-5 + 1 + \text-4 = \text-3.