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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 285 · 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 441 + 670? (a) 1100 (b) 1300 (c) 900
  2. 2.Best estimate of 153 + 149? (a) 500 (b) 100 (c) 300
  3. 3.Best estimate of 783 + 817? (a) 1800 (b) 1600 (c) 1400
  4. 4.Best estimate of 84 × 36? (a) 320 (b) 3200 (c) 32000
  5. 5.Best estimate of 87 × 74? (a) 6300 (b) 630 (c) 63000
  6. 6.Best estimate of 251 + 710? (a) 800 (b) 1000 (c) 1200
  7. 7.Best estimate of 64 × 16? (a) 120 (b) 1200 (c) 12000
  8. 8.Best estimate of 567 + 267? (a) 1100 (b) 700 (c) 900
  9. 9.Best estimate of 74 × 98? (a) 70000 (b) 700 (c) 7000
  10. 10.Best estimate of 33 × 67? (a) 2100 (b) 21000 (c) 210
  11. 11.Best estimate of 739 + 374? (a) 1100 (b) 900 (c) 1300
  12. 12.Best estimate of 817 + 421? (a) 1400 (b) 1200 (c) 1000
  13. 13.Best estimate of 419 + 559? (a) 800 (b) 1200 (c) 1000
  14. 14.Best estimate of 694 + 760? (a) 1700 (b) 1500 (c) 1300
  15. 15.Best estimate of 218 + 729? (a) 900 (b) 700 (c) 1100
  16. 16.Best estimate of 66 × 78? (a) 5600 (b) 56000 (c) 560
  17. 17.Best estimate of 33 × 60? (a) 18000 (b) 180 (c) 1800
  18. 18.Best estimate of 17 × 18? (a) 400 (b) 40 (c) 4000
  19. 19.Best estimate of 68 × 73? (a) 4900 (b) 49000 (c) 490
  20. 20.Best estimate of 27 × 50? (a) 1500 (b) 150 (c) 15000
  21. 21.Best estimate of 87 × 28? (a) 27000 (b) 270 (c) 2700
  22. 22.Best estimate of 69 × 90? (a) 630 (b) 63000 (c) 6300
  23. 23.Best estimate of 38 × 90? (a) 36000 (b) 3600 (c) 360
  24. 24.Best estimate of 53 × 58? (a) 300 (b) 30000 (c) 3000
  25. 25.Best estimate of 46 × 43? (a) 20000 (b) 200 (c) 2000
  26. 26.Best estimate of 23 × 24? (a) 4000 (b) 40 (c) 400
  27. 27.Best estimate of 338 + 710? (a) 1200 (b) 800 (c) 1000
  28. 28.Best estimate of 77 × 18? (a) 1600 (b) 16000 (c) 160
  29. 29.Best estimate of 241 + 676? (a) 1100 (b) 900 (c) 700
  30. 30.Best estimate of 695 + 325? (a) 1000 (b) 1200 (c) 800
  31. 31.Best estimate of 730 + 701? (a) 1400 (b) 1200 (c) 1600
  32. 32.Best estimate of 395 + 686? (a) 1100 (b) 900 (c) 1300
  33. 33.Best estimate of 64 × 22? (a) 12000 (b) 120 (c) 1200
  34. 34.Best estimate of 63 × 97? (a) 60000 (b) 6000 (c) 600
  35. 35.Best estimate of 83 × 91? (a) 7200 (b) 72000 (c) 720
  36. 36.Best estimate of 62 × 53? (a) 3000 (b) 30000 (c) 300
  37. 37.Best estimate of 789 + 775? (a) 1600 (b) 1400 (c) 1800
  38. 38.Best estimate of 98 × 68? (a) 700 (b) 7000 (c) 70000
  39. 39.Best estimate of 87 × 72? (a) 6300 (b) 63000 (c) 630
  40. 40.Best estimate of 31 × 69? (a) 210 (b) 2100 (c) 21000

Answer key

  1. 1100
  2. 300
  3. 1600
  4. 3200
  5. 6300
  6. 1000
  7. 1200
  8. 900
  9. 7000
  10. 2100
  11. 1100
  12. 1200
  13. 1000
  14. 1500
  15. 900
  16. 5600
  17. 1800
  18. 400
  19. 4900
  20. 1500
  21. 2700
  22. 6300
  23. 3600
  24. 3000
  25. 2000
  26. 400
  27. 1000
  28. 1600
  29. 900
  30. 1000
  31. 1400
  32. 1100
  33. 1200
  34. 6000
  35. 7200
  36. 3000
  37. 1600
  38. 7000
  39. 6300
  40. 2100

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