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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 629 · 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 535 + 340? (a) 1000 (b) 600 (c) 800
  2. 2.Best estimate of 98 × 86? (a) 90000 (b) 9000 (c) 900
  3. 3.Best estimate of 89 × 12? (a) 90 (b) 900 (c) 9000
  4. 4.Best estimate of 51 × 29? (a) 150 (b) 1500 (c) 15000
  5. 5.Best estimate of 745 + 842? (a) 1700 (b) 1300 (c) 1500
  6. 6.Best estimate of 344 + 279? (a) 800 (b) 400 (c) 600
  7. 7.Best estimate of 36 × 77? (a) 320 (b) 32000 (c) 3200
  8. 8.Best estimate of 94 × 54? (a) 450 (b) 4500 (c) 45000
  9. 9.Best estimate of 715 + 268? (a) 1200 (b) 1000 (c) 800
  10. 10.Best estimate of 324 + 403? (a) 700 (b) 500 (c) 900
  11. 11.Best estimate of 496 + 781? (a) 1500 (b) 1100 (c) 1300
  12. 12.Best estimate of 257 + 220? (a) 500 (b) 700 (c) 300
  13. 13.Best estimate of 59 × 29? (a) 180 (b) 1800 (c) 18000
  14. 14.Best estimate of 486 + 203? (a) 900 (b) 700 (c) 500
  15. 15.Best estimate of 197 + 425? (a) 600 (b) 400 (c) 800
  16. 16.Best estimate of 38 × 54? (a) 200 (b) 20000 (c) 2000
  17. 17.Best estimate of 86 × 52? (a) 450 (b) 45000 (c) 4500
  18. 18.Best estimate of 19 × 30? (a) 600 (b) 60 (c) 6000
  19. 19.Best estimate of 814 + 735? (a) 1700 (b) 1300 (c) 1500
  20. 20.Best estimate of 56 × 13? (a) 600 (b) 6000 (c) 60
  21. 21.Best estimate of 365 + 154? (a) 800 (b) 600 (c) 400
  22. 22.Best estimate of 809 + 292? (a) 1300 (b) 900 (c) 1100
  23. 23.Best estimate of 14 × 86? (a) 900 (b) 90 (c) 9000
  24. 24.Best estimate of 88 × 47? (a) 450 (b) 4500 (c) 45000
  25. 25.Best estimate of 81 × 30? (a) 2400 (b) 24000 (c) 240
  26. 26.Best estimate of 72 × 33? (a) 210 (b) 2100 (c) 21000
  27. 27.Best estimate of 66 × 62? (a) 4200 (b) 420 (c) 42000
  28. 28.Best estimate of 41 × 28? (a) 1200 (b) 12000 (c) 120
  29. 29.Best estimate of 32 × 51? (a) 15000 (b) 1500 (c) 150
  30. 30.Best estimate of 282 + 205? (a) 700 (b) 500 (c) 300
  31. 31.Best estimate of 79 × 43? (a) 3200 (b) 320 (c) 32000
  32. 32.Best estimate of 325 + 321? (a) 400 (b) 800 (c) 600
  33. 33.Best estimate of 13 × 71? (a) 7000 (b) 700 (c) 70
  34. 34.Best estimate of 71 × 87? (a) 630 (b) 63000 (c) 6300
  35. 35.Best estimate of 170 + 340? (a) 700 (b) 500 (c) 300
  36. 36.Best estimate of 872 + 204? (a) 1300 (b) 1100 (c) 900
  37. 37.Best estimate of 40 × 21? (a) 800 (b) 8000 (c) 80
  38. 38.Best estimate of 98 × 76? (a) 800 (b) 8000 (c) 80000
  39. 39.Best estimate of 722 + 500? (a) 1400 (b) 1200 (c) 1000
  40. 40.Best estimate of 39 × 37? (a) 16000 (b) 1600 (c) 160

Answer key

  1. 800
  2. 9000
  3. 900
  4. 1500
  5. 1500
  6. 600
  7. 3200
  8. 4500
  9. 1000
  10. 700
  11. 1300
  12. 500
  13. 1800
  14. 700
  15. 600
  16. 2000
  17. 4500
  18. 600
  19. 1500
  20. 600
  21. 600
  22. 1100
  23. 900
  24. 4500
  25. 2400
  26. 2100
  27. 4200
  28. 1200
  29. 1500
  30. 500
  31. 3200
  32. 600
  33. 700
  34. 6300
  35. 500
  36. 1100
  37. 800
  38. 8000
  39. 1200
  40. 1600

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