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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 948 · 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 20 × 52? (a) 10000 (b) 100 (c) 1000
  2. 2.Best estimate of 47 × 46? (a) 2500 (b) 25000 (c) 250
  3. 3.Best estimate of 802 + 699? (a) 1500 (b) 1700 (c) 1300
  4. 4.Best estimate of 675 + 212? (a) 700 (b) 1100 (c) 900
  5. 5.Best estimate of 76 × 70? (a) 56000 (b) 5600 (c) 560
  6. 6.Best estimate of 643 + 570? (a) 1200 (b) 1400 (c) 1000
  7. 7.Best estimate of 94 × 82? (a) 72000 (b) 7200 (c) 720
  8. 8.Best estimate of 627 + 296? (a) 900 (b) 700 (c) 1100
  9. 9.Best estimate of 41 × 50? (a) 200 (b) 20000 (c) 2000
  10. 10.Best estimate of 33 × 81? (a) 2400 (b) 240 (c) 24000
  11. 11.Best estimate of 566 + 120? (a) 700 (b) 900 (c) 500
  12. 12.Best estimate of 686 + 368? (a) 1100 (b) 1300 (c) 900
  13. 13.Best estimate of 43 × 69? (a) 28000 (b) 280 (c) 2800
  14. 14.Best estimate of 67 × 62? (a) 42000 (b) 420 (c) 4200
  15. 15.Best estimate of 362 + 839? (a) 1200 (b) 1000 (c) 1400
  16. 16.Best estimate of 12 × 67? (a) 700 (b) 7000 (c) 70
  17. 17.Best estimate of 471 + 131? (a) 400 (b) 600 (c) 800
  18. 18.Best estimate of 576 + 467? (a) 1100 (b) 900 (c) 1300
  19. 19.Best estimate of 52 × 81? (a) 4000 (b) 400 (c) 40000
  20. 20.Best estimate of 251 + 264? (a) 400 (b) 800 (c) 600
  21. 21.Best estimate of 216 + 272? (a) 300 (b) 500 (c) 700
  22. 22.Best estimate of 19 × 73? (a) 140 (b) 14000 (c) 1400
  23. 23.Best estimate of 87 × 83? (a) 7200 (b) 72000 (c) 720
  24. 24.Best estimate of 368 + 504? (a) 700 (b) 1100 (c) 900
  25. 25.Best estimate of 81 × 29? (a) 24000 (b) 240 (c) 2400
  26. 26.Best estimate of 96 × 73? (a) 70000 (b) 7000 (c) 700
  27. 27.Best estimate of 29 × 21? (a) 600 (b) 6000 (c) 60
  28. 28.Best estimate of 81 × 93? (a) 72000 (b) 7200 (c) 720
  29. 29.Best estimate of 183 + 796? (a) 800 (b) 1000 (c) 1200
  30. 30.Best estimate of 792 + 343? (a) 1100 (b) 900 (c) 1300
  31. 31.Best estimate of 755 + 343? (a) 900 (b) 1300 (c) 1100
  32. 32.Best estimate of 220 + 733? (a) 1100 (b) 700 (c) 900
  33. 33.Best estimate of 505 + 655? (a) 1400 (b) 1000 (c) 1200
  34. 34.Best estimate of 44 × 13? (a) 400 (b) 4000 (c) 40
  35. 35.Best estimate of 67 × 44? (a) 2800 (b) 28000 (c) 280
  36. 36.Best estimate of 37 × 76? (a) 32000 (b) 3200 (c) 320
  37. 37.Best estimate of 630 + 463? (a) 900 (b) 1100 (c) 1300
  38. 38.Best estimate of 20 × 92? (a) 180 (b) 18000 (c) 1800
  39. 39.Best estimate of 24 × 22? (a) 40 (b) 400 (c) 4000
  40. 40.Best estimate of 73 × 52? (a) 3500 (b) 350 (c) 35000

Answer key

  1. 1000
  2. 2500
  3. 1500
  4. 900
  5. 5600
  6. 1200
  7. 7200
  8. 900
  9. 2000
  10. 2400
  11. 700
  12. 1100
  13. 2800
  14. 4200
  15. 1200
  16. 700
  17. 600
  18. 1100
  19. 4000
  20. 600
  21. 500
  22. 1400
  23. 7200
  24. 900
  25. 2400
  26. 7000
  27. 600
  28. 7200
  29. 1000
  30. 1100
  31. 1100
  32. 900
  33. 1200
  34. 400
  35. 2800
  36. 3200
  37. 1100
  38. 1800
  39. 400
  40. 3500

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