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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 89 · 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 43 × 90? (a) 360 (b) 3600 (c) 36000
  2. 2.Best estimate of 49 × 22? (a) 10000 (b) 1000 (c) 100
  3. 3.Best estimate of 96 × 36? (a) 4000 (b) 400 (c) 40000
  4. 4.Best estimate of 24 × 31? (a) 600 (b) 6000 (c) 60
  5. 5.Best estimate of 644 + 544? (a) 1100 (b) 1300 (c) 900
  6. 6.Best estimate of 76 × 54? (a) 400 (b) 40000 (c) 4000
  7. 7.Best estimate of 373 + 281? (a) 700 (b) 900 (c) 500
  8. 8.Best estimate of 754 + 587? (a) 1600 (b) 1200 (c) 1400
  9. 9.Best estimate of 90 × 94? (a) 8100 (b) 81000 (c) 810
  10. 10.Best estimate of 209 + 335? (a) 700 (b) 500 (c) 300
  11. 11.Best estimate of 568 + 428? (a) 1200 (b) 800 (c) 1000
  12. 12.Best estimate of 210 + 561? (a) 1000 (b) 800 (c) 600
  13. 13.Best estimate of 418 + 129? (a) 700 (b) 300 (c) 500
  14. 14.Best estimate of 616 + 160? (a) 800 (b) 1000 (c) 600
  15. 15.Best estimate of 158 + 381? (a) 600 (b) 800 (c) 400
  16. 16.Best estimate of 225 + 202? (a) 400 (b) 600 (c) 200
  17. 17.Best estimate of 693 + 260? (a) 1200 (b) 800 (c) 1000
  18. 18.Best estimate of 27 × 74? (a) 210 (b) 2100 (c) 21000
  19. 19.Best estimate of 26 × 36? (a) 1200 (b) 12000 (c) 120
  20. 20.Best estimate of 73 × 37? (a) 2800 (b) 28000 (c) 280
  21. 21.Best estimate of 69 × 26? (a) 2100 (b) 21000 (c) 210
  22. 22.Best estimate of 64 × 32? (a) 1800 (b) 180 (c) 18000
  23. 23.Best estimate of 73 × 57? (a) 420 (b) 4200 (c) 42000
  24. 24.Best estimate of 28 × 27? (a) 9000 (b) 900 (c) 90
  25. 25.Best estimate of 30 × 61? (a) 180 (b) 1800 (c) 18000
  26. 26.Best estimate of 79 × 92? (a) 7200 (b) 720 (c) 72000
  27. 27.Best estimate of 54 × 39? (a) 20000 (b) 200 (c) 2000
  28. 28.Best estimate of 694 + 192? (a) 700 (b) 1100 (c) 900
  29. 29.Best estimate of 68 × 57? (a) 4200 (b) 420 (c) 42000
  30. 30.Best estimate of 32 × 41? (a) 120 (b) 12000 (c) 1200
  31. 31.Best estimate of 59 × 53? (a) 300 (b) 30000 (c) 3000
  32. 32.Best estimate of 691 + 805? (a) 1300 (b) 1700 (c) 1500
  33. 33.Best estimate of 458 + 535? (a) 800 (b) 1200 (c) 1000
  34. 34.Best estimate of 136 + 525? (a) 600 (b) 400 (c) 800
  35. 35.Best estimate of 94 × 63? (a) 540 (b) 5400 (c) 54000
  36. 36.Best estimate of 16 × 69? (a) 1400 (b) 140 (c) 14000
  37. 37.Best estimate of 616 + 482? (a) 1100 (b) 900 (c) 1300
  38. 38.Best estimate of 71 × 26? (a) 2100 (b) 21000 (c) 210
  39. 39.Best estimate of 860 + 818? (a) 1500 (b) 1700 (c) 1900
  40. 40.Best estimate of 816 + 293? (a) 1300 (b) 900 (c) 1100

Answer key

  1. 3600
  2. 1000
  3. 4000
  4. 600
  5. 1100
  6. 4000
  7. 700
  8. 1400
  9. 8100
  10. 500
  11. 1000
  12. 800
  13. 500
  14. 800
  15. 600
  16. 400
  17. 1000
  18. 2100
  19. 1200
  20. 2800
  21. 2100
  22. 1800
  23. 4200
  24. 900
  25. 1800
  26. 7200
  27. 2000
  28. 900
  29. 4200
  30. 1200
  31. 3000
  32. 1500
  33. 1000
  34. 600
  35. 5400
  36. 1400
  37. 1100
  38. 2100
  39. 1700
  40. 1100

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