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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 237 · 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 17 × 26? (a) 60 (b) 600 (c) 6000
  2. 2.Best estimate of 760 + 566? (a) 1400 (b) 1600 (c) 1200
  3. 3.Best estimate of 19 × 56? (a) 1200 (b) 12000 (c) 120
  4. 4.Best estimate of 853 + 169? (a) 1100 (b) 1300 (c) 900
  5. 5.Best estimate of 621 + 844? (a) 1400 (b) 1600 (c) 1200
  6. 6.Best estimate of 649 + 668? (a) 1300 (b) 1100 (c) 1500
  7. 7.Best estimate of 771 + 274? (a) 1300 (b) 1100 (c) 900
  8. 8.Best estimate of 70 × 66? (a) 4900 (b) 49000 (c) 490
  9. 9.Best estimate of 151 + 267? (a) 700 (b) 500 (c) 300
  10. 10.Best estimate of 71 × 88? (a) 630 (b) 6300 (c) 63000
  11. 11.Best estimate of 700 + 532? (a) 1200 (b) 1400 (c) 1000
  12. 12.Best estimate of 78 × 21? (a) 1600 (b) 16000 (c) 160
  13. 13.Best estimate of 44 × 57? (a) 240 (b) 2400 (c) 24000
  14. 14.Best estimate of 576 + 432? (a) 1200 (b) 800 (c) 1000
  15. 15.Best estimate of 89 × 64? (a) 5400 (b) 540 (c) 54000
  16. 16.Best estimate of 271 + 498? (a) 800 (b) 600 (c) 1000
  17. 17.Best estimate of 133 + 567? (a) 500 (b) 900 (c) 700
  18. 18.Best estimate of 57 × 60? (a) 3600 (b) 360 (c) 36000
  19. 19.Best estimate of 689 + 661? (a) 1400 (b) 1600 (c) 1200
  20. 20.Best estimate of 710 + 746? (a) 1400 (b) 1200 (c) 1600
  21. 21.Best estimate of 371 + 818? (a) 1000 (b) 1400 (c) 1200
  22. 22.Best estimate of 824 + 577? (a) 1600 (b) 1400 (c) 1200
  23. 23.Best estimate of 161 + 202? (a) 600 (b) 200 (c) 400
  24. 24.Best estimate of 92 × 90? (a) 8100 (b) 81000 (c) 810
  25. 25.Best estimate of 28 × 14? (a) 3000 (b) 300 (c) 30
  26. 26.Best estimate of 41 × 74? (a) 28000 (b) 2800 (c) 280
  27. 27.Best estimate of 56 × 90? (a) 54000 (b) 540 (c) 5400
  28. 28.Best estimate of 69 × 57? (a) 4200 (b) 42000 (c) 420
  29. 29.Best estimate of 22 × 91? (a) 180 (b) 18000 (c) 1800
  30. 30.Best estimate of 31 × 28? (a) 90 (b) 900 (c) 9000
  31. 31.Best estimate of 78 × 36? (a) 3200 (b) 320 (c) 32000
  32. 32.Best estimate of 69 × 14? (a) 70 (b) 700 (c) 7000
  33. 33.Best estimate of 34 × 91? (a) 27000 (b) 2700 (c) 270
  34. 34.Best estimate of 257 + 214? (a) 500 (b) 700 (c) 300
  35. 35.Best estimate of 88 × 50? (a) 4500 (b) 450 (c) 45000
  36. 36.Best estimate of 31 × 27? (a) 9000 (b) 900 (c) 90
  37. 37.Best estimate of 76 × 68? (a) 56000 (b) 5600 (c) 560
  38. 38.Best estimate of 41 × 43? (a) 16000 (b) 160 (c) 1600
  39. 39.Best estimate of 749 + 480? (a) 1200 (b) 1400 (c) 1000
  40. 40.Best estimate of 20 × 17? (a) 400 (b) 4000 (c) 40

Answer key

  1. 600
  2. 1400
  3. 1200
  4. 1100
  5. 1400
  6. 1300
  7. 1100
  8. 4900
  9. 500
  10. 6300
  11. 1200
  12. 1600
  13. 2400
  14. 1000
  15. 5400
  16. 800
  17. 700
  18. 3600
  19. 1400
  20. 1400
  21. 1200
  22. 1400
  23. 400
  24. 8100
  25. 300
  26. 2800
  27. 5400
  28. 4200
  29. 1800
  30. 900
  31. 3200
  32. 700
  33. 2700
  34. 500
  35. 4500
  36. 900
  37. 5600
  38. 1600
  39. 1200
  40. 400

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