Multi-step problems with positive and negative numbers, and checking they make sense

Answer Key - Grade 7 Math Worksheet - Building Confidence

Circle the best answer, or write your answer on the line.

1. 1.

   Bo's kite is 12 m high. Each minute its height changes by -1.5 m, for 5 minutes. What is the total change in height, and how high is the kite then?

   -7.5, 4.5
2. 2.

   Esme's robot starts at -2.5 on a number line. Each step changes its place by 0.75, for 7 steps. What is the total change, and where does the robot end?

   5.25, 2.75
3. 3.

   Jun watches a whale at -6.5 m (below the surface is negative). Each second its depth changes by -2.5 m, for 3 seconds. What is the total change, and where is it then?

   -7.5, -14

4. Read this first

   Use this

   A table of four rows. Row | As given | As a decimal: 1 | -3/4 | -0.75; 2 | 0.5 | 0.5; 3 | -1/4 | -0.25; 4 | 2 | 2.

5. 4.

   Luz logs how a pond's water level changes each day, in cm. The table shows each change two ways. What is the total change for the four days?

   1.5

6. Use this

   A table of four rows. Row | As given | As a decimal: 1 | 1/2 | 0.5; 2 | -1.25 | -1.25; 3 | 1.5 | 1.5; 4 | -3 | -3.

7. 5.

   Milo logs how the temperature changes on four days, in degrees. The table shows each change two ways. What is the total change?

   -2.25

8. Use this

   A table of four rows. Row | As given | As a decimal: 1 | -1.5 | -1.5; 2 | 3/4 | 0.75; 3 | 0.25 | 0.25; 4 | -1/4 | -0.25.

9. 6.

   Noah logs how a game score changes in four rounds, in points. The table shows each change two ways. What is the total change?

   -0.75

10. Use this

    A table of four rows. Row | As given | As a decimal: 1 | 2.5 | 2.5; 2 | -1/4 | -0.25; 3 | -3/4 | -0.75; 4 | 1/4 | 0.25.

11. 7.

    Pia logs how the thickness of a pond's ice changes on four days, in cm. The table shows each change two ways. What is the total change?

    1.75
12. 8.

    Ren multiplies (-4.9) × 3.1 on a phone calculator, but the screen is smudged. Use a quick estimate. Which answer makes sense?

    • -1.519
    • -15.19
    • -151.9
    • 15.19
13. 9.

    Tala multiplies 6.8 × (-2.1) on paper, but a drip hides the answer. Use a quick estimate. Which answer makes sense?

    • 14.28
    • -1.428
    • -14.28
    • -142.8
14. 10.

    Ari multiplies 4.2 × (-3.8) before the bell, but the answer is smudged. Use a quick estimate. Which answer makes sense?

    • -15.96
    • 15.96
    • -159.6
    • -1.596