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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 123 · 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 290 + 203? (a) 700 (b) 500 (c) 300
  2. 2.Best estimate of 97 × 54? (a) 5000 (b) 500 (c) 50000
  3. 3.Best estimate of 457 + 473? (a) 1000 (b) 1200 (c) 800
  4. 4.Best estimate of 60 × 54? (a) 300 (b) 3000 (c) 30000
  5. 5.Best estimate of 579 + 636? (a) 1200 (b) 1400 (c) 1000
  6. 6.Best estimate of 549 + 628? (a) 900 (b) 1100 (c) 1300
  7. 7.Best estimate of 48 × 87? (a) 4500 (b) 450 (c) 45000
  8. 8.Best estimate of 132 + 151? (a) 300 (b) 100 (c) 500
  9. 9.Best estimate of 71 × 91? (a) 63000 (b) 6300 (c) 630
  10. 10.Best estimate of 19 × 21? (a) 4000 (b) 400 (c) 40
  11. 11.Best estimate of 50 × 73? (a) 3500 (b) 35000 (c) 350
  12. 12.Best estimate of 295 + 517? (a) 600 (b) 800 (c) 1000
  13. 13.Best estimate of 155 + 787? (a) 1200 (b) 800 (c) 1000
  14. 14.Best estimate of 293 + 465? (a) 800 (b) 1000 (c) 600
  15. 15.Best estimate of 24 × 22? (a) 40 (b) 4000 (c) 400
  16. 16.Best estimate of 379 + 160? (a) 400 (b) 800 (c) 600
  17. 17.Best estimate of 223 + 511? (a) 900 (b) 700 (c) 500
  18. 18.Best estimate of 66 × 29? (a) 210 (b) 21000 (c) 2100
  19. 19.Best estimate of 36 × 32? (a) 120 (b) 12000 (c) 1200
  20. 20.Best estimate of 14 × 87? (a) 90 (b) 9000 (c) 900
  21. 21.Best estimate of 22 × 96? (a) 200 (b) 20000 (c) 2000
  22. 22.Best estimate of 80 × 70? (a) 5600 (b) 56000 (c) 560
  23. 23.Best estimate of 56 × 67? (a) 420 (b) 42000 (c) 4200
  24. 24.Best estimate of 12 × 54? (a) 50 (b) 5000 (c) 500
  25. 25.Best estimate of 70 × 36? (a) 28000 (b) 2800 (c) 280
  26. 26.Best estimate of 38 × 87? (a) 3600 (b) 360 (c) 36000
  27. 27.Best estimate of 72 × 16? (a) 1400 (b) 14000 (c) 140
  28. 28.Best estimate of 224 + 167? (a) 600 (b) 200 (c) 400
  29. 29.Best estimate of 14 × 68? (a) 700 (b) 7000 (c) 70
  30. 30.Best estimate of 89 × 51? (a) 4500 (b) 45000 (c) 450
  31. 31.Best estimate of 48 × 39? (a) 200 (b) 2000 (c) 20000
  32. 32.Best estimate of 24 × 60? (a) 12000 (b) 1200 (c) 120
  33. 33.Best estimate of 21 × 77? (a) 160 (b) 1600 (c) 16000
  34. 34.Best estimate of 26 × 97? (a) 3000 (b) 300 (c) 30000
  35. 35.Best estimate of 76 × 96? (a) 80000 (b) 8000 (c) 800
  36. 36.Best estimate of 694 + 493? (a) 1000 (b) 1200 (c) 1400
  37. 37.Best estimate of 49 × 76? (a) 400 (b) 4000 (c) 40000
  38. 38.Best estimate of 14 × 23? (a) 20 (b) 200 (c) 2000
  39. 39.Best estimate of 89 × 16? (a) 1800 (b) 18000 (c) 180
  40. 40.Best estimate of 54 × 89? (a) 4500 (b) 450 (c) 45000

Answer key

  1. 500
  2. 5000
  3. 1000
  4. 3000
  5. 1200
  6. 1100
  7. 4500
  8. 300
  9. 6300
  10. 400
  11. 3500
  12. 800
  13. 1000
  14. 800
  15. 400
  16. 600
  17. 700
  18. 2100
  19. 1200
  20. 900
  21. 2000
  22. 5600
  23. 4200
  24. 500
  25. 2800
  26. 3600
  27. 1400
  28. 400
  29. 700
  30. 4500
  31. 2000
  32. 1200
  33. 1600
  34. 3000
  35. 8000
  36. 1200
  37. 4000
  38. 200
  39. 1800
  40. 4500

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