L12 · Multiply and divide with negative numbers

1. 1.

   Compute (7) × (−7).

   Answer. −49

   7 × −7 = −49.

2. 2.

   Compute (28) ÷ (−4).

   Answer. −7

   28 ÷ −4 = −7.

3. 3.

   Compute (−5) × (5).

   Answer. −25

   −5 × 5 = −25.

4. 4.

   Compute (−36) ÷ (6).

   Answer. −6

   −36 ÷ 6 = −6.

5. 5.

   Compute (−7) × (8). Then Grace needs 2 of that amount. What is the total they need?

   Answer. −112

   −7 × 8 = −56. Then multiply by 2: −112.

6. 6.

   Compute (−28) ÷ (7). Then Mei needs 5 of that amount. What is the total they need?

   Answer. −20

   −28 ÷ 7 = −4. Then multiply by 5: −20.

7. 7.

   Compute (8) × (−6). Then Sam needs 3 of that amount. What is the total they need?

   Answer. −144

   8 × −6 = −48. Then multiply by 3: −144.

8. 8.

   Compute (−21) ÷ (−3). Then Nora needs 2 of that amount. What is the total they need?

   Answer. 14

   −21 ÷ −3 = 7. Then multiply by 2: 14.

9. 9.

   Compute (6) × (−2). Then Mei needs 3 of that amount. What is the total they need?

   Answer. −36

   6 × −2 = −12. Then multiply by 3: −36.

10. 10.

    Compute (−24) ÷ (8). Then Theo needs 4 of that amount. What is the total they need?

    Answer. −12

    −24 ÷ 8 = −3. Then multiply by 4: −12.

11. 11.

    Think

    Theo tried this problem:
    Compute (−8) × (9).
    Theo wrote −144. That is not correct. What is the right answer?

    Answer. −72

    Theo’s answer −144 is off. −8 × 9 = −72.

12. 12.

    Think

    Owen tried this problem:
    Compute (8) ÷ (2).
    Owen wrote 5. That is not correct. What is the right answer?

    Answer. 4

    Owen’s answer 5 is off. 8 ÷ 2 = 4.

Original extra practice. Keys are computed from the items, not guessed.