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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 272 · 40 questions
TalentJR

How to do it in your head (Round, then work): Round each number: 2-digit numbers to the nearest ten, 3-digit numbers to the nearest hundred. Do the easy sum with the round numbers. Choose the option closest to your estimate.

NameDateTime takenScore ___ / 40
  1. 1.Best estimate of 84 × 79? (a) 6400 (b) 64000 (c) 640
  2. 2.Best estimate of 38 × 24? (a) 800 (b) 8000 (c) 80
  3. 3.Best estimate of 747 + 298? (a) 1000 (b) 1200 (c) 800
  4. 4.Best estimate of 90 × 62? (a) 54000 (b) 5400 (c) 540
  5. 5.Best estimate of 812 + 756? (a) 1600 (b) 1400 (c) 1800
  6. 6.Best estimate of 23 × 50? (a) 10000 (b) 1000 (c) 100
  7. 7.Best estimate of 43 × 24? (a) 80 (b) 8000 (c) 800
  8. 8.Best estimate of 52 × 86? (a) 45000 (b) 450 (c) 4500
  9. 9.Best estimate of 26 × 40? (a) 120 (b) 12000 (c) 1200
  10. 10.Best estimate of 46 × 44? (a) 20000 (b) 2000 (c) 200
  11. 11.Best estimate of 58 × 26? (a) 18000 (b) 180 (c) 1800
  12. 12.Best estimate of 37 × 69? (a) 2800 (b) 28000 (c) 280
  13. 13.Best estimate of 34 × 18? (a) 60 (b) 600 (c) 6000
  14. 14.Best estimate of 84 × 32? (a) 24000 (b) 240 (c) 2400
  15. 15.Best estimate of 126 + 373? (a) 500 (b) 700 (c) 300
  16. 16.Best estimate of 143 + 505? (a) 400 (b) 600 (c) 800
  17. 17.Best estimate of 90 × 82? (a) 72000 (b) 7200 (c) 720
  18. 18.Best estimate of 24 × 38? (a) 8000 (b) 800 (c) 80
  19. 19.Best estimate of 484 + 199? (a) 500 (b) 900 (c) 700
  20. 20.Best estimate of 26 × 57? (a) 1800 (b) 18000 (c) 180
  21. 21.Best estimate of 41 × 76? (a) 320 (b) 3200 (c) 32000
  22. 22.Best estimate of 221 + 819? (a) 1200 (b) 800 (c) 1000
  23. 23.Best estimate of 22 × 24? (a) 400 (b) 4000 (c) 40
  24. 24.Best estimate of 391 + 158? (a) 800 (b) 600 (c) 400
  25. 25.Best estimate of 14 × 86? (a) 9000 (b) 900 (c) 90
  26. 26.Best estimate of 73 × 26? (a) 210 (b) 21000 (c) 2100
  27. 27.Best estimate of 475 + 128? (a) 600 (b) 400 (c) 800
  28. 28.Best estimate of 193 + 125? (a) 100 (b) 300 (c) 500
  29. 29.Best estimate of 66 × 36? (a) 28000 (b) 2800 (c) 280
  30. 30.Best estimate of 759 + 197? (a) 1200 (b) 800 (c) 1000
  31. 31.Best estimate of 86 × 79? (a) 72000 (b) 720 (c) 7200
  32. 32.Best estimate of 389 + 298? (a) 900 (b) 500 (c) 700
  33. 33.Best estimate of 847 + 745? (a) 1300 (b) 1500 (c) 1700
  34. 34.Best estimate of 39 × 71? (a) 28000 (b) 280 (c) 2800
  35. 35.Best estimate of 96 × 30? (a) 3000 (b) 30000 (c) 300
  36. 36.Best estimate of 29 × 61? (a) 1800 (b) 180 (c) 18000
  37. 37.Best estimate of 290 + 711? (a) 1000 (b) 1200 (c) 800
  38. 38.Best estimate of 640 + 379? (a) 1200 (b) 1000 (c) 800
  39. 39.Best estimate of 767 + 875? (a) 1700 (b) 1500 (c) 1900
  40. 40.Best estimate of 83 × 24? (a) 1600 (b) 160 (c) 16000

Answer key

  1. 6400
  2. 800
  3. 1000
  4. 5400
  5. 1600
  6. 1000
  7. 800
  8. 4500
  9. 1200
  10. 2000
  11. 1800
  12. 2800
  13. 600
  14. 2400
  15. 500
  16. 600
  17. 7200
  18. 800
  19. 700
  20. 1800
  21. 3200
  22. 1000
  23. 400
  24. 600
  25. 900
  26. 2100
  27. 600
  28. 300
  29. 2800
  30. 1000
  31. 7200
  32. 700
  33. 1500
  34. 2800
  35. 3000
  36. 1800
  37. 1000
  38. 1000
  39. 1700
  40. 1600

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