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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 611 · 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 68 × 33? (a) 21000 (b) 210 (c) 2100
  2. 2.Best estimate of 81 × 26? (a) 24000 (b) 2400 (c) 240
  3. 3.Best estimate of 718 + 297? (a) 1000 (b) 800 (c) 1200
  4. 4.Best estimate of 141 + 318? (a) 200 (b) 400 (c) 600
  5. 5.Best estimate of 77 × 34? (a) 24000 (b) 240 (c) 2400
  6. 6.Best estimate of 17 × 29? (a) 600 (b) 60 (c) 6000
  7. 7.Best estimate of 653 + 315? (a) 800 (b) 1200 (c) 1000
  8. 8.Best estimate of 63 × 33? (a) 18000 (b) 1800 (c) 180
  9. 9.Best estimate of 42 × 46? (a) 2000 (b) 200 (c) 20000
  10. 10.Best estimate of 587 + 377? (a) 800 (b) 1200 (c) 1000
  11. 11.Best estimate of 32 × 33? (a) 900 (b) 90 (c) 9000
  12. 12.Best estimate of 748 + 398? (a) 1100 (b) 1300 (c) 900
  13. 13.Best estimate of 461 + 336? (a) 600 (b) 800 (c) 1000
  14. 14.Best estimate of 29 × 89? (a) 27000 (b) 2700 (c) 270
  15. 15.Best estimate of 486 + 461? (a) 800 (b) 1000 (c) 1200
  16. 16.Best estimate of 726 + 610? (a) 1500 (b) 1100 (c) 1300
  17. 17.Best estimate of 19 × 14? (a) 200 (b) 2000 (c) 20
  18. 18.Best estimate of 42 × 31? (a) 12000 (b) 1200 (c) 120
  19. 19.Best estimate of 39 × 20? (a) 8000 (b) 80 (c) 800
  20. 20.Best estimate of 175 + 520? (a) 700 (b) 900 (c) 500
  21. 21.Best estimate of 683 + 140? (a) 800 (b) 1000 (c) 600
  22. 22.Best estimate of 86 × 29? (a) 27000 (b) 270 (c) 2700
  23. 23.Best estimate of 748 + 829? (a) 1700 (b) 1300 (c) 1500
  24. 24.Best estimate of 60 × 30? (a) 1800 (b) 18000 (c) 180
  25. 25.Best estimate of 26 × 66? (a) 21000 (b) 2100 (c) 210
  26. 26.Best estimate of 588 + 746? (a) 1300 (b) 1500 (c) 1100
  27. 27.Best estimate of 23 × 51? (a) 1000 (b) 100 (c) 10000
  28. 28.Best estimate of 71 × 76? (a) 560 (b) 56000 (c) 5600
  29. 29.Best estimate of 53 × 46? (a) 25000 (b) 2500 (c) 250
  30. 30.Best estimate of 32 × 16? (a) 600 (b) 6000 (c) 60
  31. 31.Best estimate of 77 × 12? (a) 80 (b) 8000 (c) 800
  32. 32.Best estimate of 23 × 56? (a) 12000 (b) 120 (c) 1200
  33. 33.Best estimate of 401 + 552? (a) 1000 (b) 800 (c) 1200
  34. 34.Best estimate of 43 × 43? (a) 160 (b) 1600 (c) 16000
  35. 35.Best estimate of 586 + 193? (a) 800 (b) 600 (c) 1000
  36. 36.Best estimate of 17 × 41? (a) 800 (b) 8000 (c) 80
  37. 37.Best estimate of 18 × 37? (a) 80 (b) 8000 (c) 800
  38. 38.Best estimate of 22 × 64? (a) 12000 (b) 120 (c) 1200
  39. 39.Best estimate of 93 × 86? (a) 810 (b) 8100 (c) 81000
  40. 40.Best estimate of 60 × 82? (a) 48000 (b) 480 (c) 4800

Answer key

  1. 2100
  2. 2400
  3. 1000
  4. 400
  5. 2400
  6. 600
  7. 1000
  8. 1800
  9. 2000
  10. 1000
  11. 900
  12. 1100
  13. 800
  14. 2700
  15. 1000
  16. 1300
  17. 200
  18. 1200
  19. 800
  20. 700
  21. 800
  22. 2700
  23. 1500
  24. 1800
  25. 2100
  26. 1300
  27. 1000
  28. 5600
  29. 2500
  30. 600
  31. 800
  32. 1200
  33. 1000
  34. 1600
  35. 800
  36. 800
  37. 800
  38. 1200
  39. 8100
  40. 4800

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