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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 36 · 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 90 × 57? (a) 540 (b) 5400 (c) 54000
  2. 2.Best estimate of 54 × 28? (a) 15000 (b) 150 (c) 1500
  3. 3.Best estimate of 47 × 40? (a) 20000 (b) 2000 (c) 200
  4. 4.Best estimate of 28 × 53? (a) 150 (b) 1500 (c) 15000
  5. 5.Best estimate of 265 + 235? (a) 300 (b) 700 (c) 500
  6. 6.Best estimate of 43 × 87? (a) 36000 (b) 3600 (c) 360
  7. 7.Best estimate of 26 × 49? (a) 1500 (b) 150 (c) 15000
  8. 8.Best estimate of 78 × 88? (a) 72000 (b) 7200 (c) 720
  9. 9.Best estimate of 288 + 266? (a) 600 (b) 400 (c) 800
  10. 10.Best estimate of 23 × 24? (a) 40 (b) 4000 (c) 400
  11. 11.Best estimate of 14 × 23? (a) 200 (b) 2000 (c) 20
  12. 12.Best estimate of 429 + 877? (a) 1300 (b) 1500 (c) 1100
  13. 13.Best estimate of 26 × 20? (a) 6000 (b) 60 (c) 600
  14. 14.Best estimate of 384 + 149? (a) 500 (b) 700 (c) 300
  15. 15.Best estimate of 235 + 880? (a) 900 (b) 1300 (c) 1100
  16. 16.Best estimate of 63 × 54? (a) 300 (b) 30000 (c) 3000
  17. 17.Best estimate of 628 + 289? (a) 700 (b) 900 (c) 1100
  18. 18.Best estimate of 61 × 50? (a) 300 (b) 30000 (c) 3000
  19. 19.Best estimate of 84 × 29? (a) 2400 (b) 240 (c) 24000
  20. 20.Best estimate of 44 × 47? (a) 20000 (b) 2000 (c) 200
  21. 21.Best estimate of 273 + 497? (a) 1000 (b) 600 (c) 800
  22. 22.Best estimate of 486 + 205? (a) 700 (b) 900 (c) 500
  23. 23.Best estimate of 386 + 753? (a) 1400 (b) 1000 (c) 1200
  24. 24.Best estimate of 368 + 680? (a) 1100 (b) 1300 (c) 900
  25. 25.Best estimate of 135 + 834? (a) 700 (b) 900 (c) 1100
  26. 26.Best estimate of 66 × 18? (a) 14000 (b) 1400 (c) 140
  27. 27.Best estimate of 18 × 36? (a) 8000 (b) 800 (c) 80
  28. 28.Best estimate of 646 + 767? (a) 1600 (b) 1400 (c) 1200
  29. 29.Best estimate of 191 + 838? (a) 1000 (b) 800 (c) 1200
  30. 30.Best estimate of 16 × 12? (a) 200 (b) 20 (c) 2000
  31. 31.Best estimate of 16 × 14? (a) 200 (b) 20 (c) 2000
  32. 32.Best estimate of 78 × 98? (a) 8000 (b) 800 (c) 80000
  33. 33.Best estimate of 561 + 238? (a) 600 (b) 800 (c) 1000
  34. 34.Best estimate of 16 × 96? (a) 20000 (b) 200 (c) 2000
  35. 35.Best estimate of 74 × 98? (a) 7000 (b) 700 (c) 70000
  36. 36.Best estimate of 27 × 87? (a) 2700 (b) 27000 (c) 270
  37. 37.Best estimate of 33 × 20? (a) 600 (b) 6000 (c) 60
  38. 38.Best estimate of 67 × 23? (a) 14000 (b) 140 (c) 1400
  39. 39.Best estimate of 859 + 592? (a) 1300 (b) 1500 (c) 1700
  40. 40.Best estimate of 61 × 96? (a) 60000 (b) 600 (c) 6000

Answer key

  1. 5400
  2. 1500
  3. 2000
  4. 1500
  5. 500
  6. 3600
  7. 1500
  8. 7200
  9. 600
  10. 400
  11. 200
  12. 1300
  13. 600
  14. 500
  15. 1100
  16. 3000
  17. 900
  18. 3000
  19. 2400
  20. 2000
  21. 800
  22. 700
  23. 1200
  24. 1100
  25. 900
  26. 1400
  27. 800
  28. 1400
  29. 1000
  30. 200
  31. 200
  32. 8000
  33. 800
  34. 2000
  35. 7000
  36. 2700
  37. 600
  38. 1400
  39. 1500
  40. 6000

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