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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 524 · 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 22 × 94? (a) 180 (b) 1800 (c) 18000
  2. 2.Best estimate of 58 × 31? (a) 180 (b) 18000 (c) 1800
  3. 3.Best estimate of 72 × 54? (a) 35000 (b) 3500 (c) 350
  4. 4.Best estimate of 20 × 12? (a) 2000 (b) 200 (c) 20
  5. 5.Best estimate of 16 × 33? (a) 600 (b) 6000 (c) 60
  6. 6.Best estimate of 51 × 89? (a) 4500 (b) 45000 (c) 450
  7. 7.Best estimate of 179 + 129? (a) 500 (b) 300 (c) 100
  8. 8.Best estimate of 38 × 89? (a) 360 (b) 36000 (c) 3600
  9. 9.Best estimate of 39 × 60? (a) 24000 (b) 240 (c) 2400
  10. 10.Best estimate of 609 + 536? (a) 1300 (b) 900 (c) 1100
  11. 11.Best estimate of 192 + 151? (a) 200 (b) 600 (c) 400
  12. 12.Best estimate of 614 + 289? (a) 900 (b) 1100 (c) 700
  13. 13.Best estimate of 443 + 763? (a) 1000 (b) 1200 (c) 1400
  14. 14.Best estimate of 53 × 66? (a) 3500 (b) 350 (c) 35000
  15. 15.Best estimate of 648 + 281? (a) 700 (b) 1100 (c) 900
  16. 16.Best estimate of 22 × 36? (a) 800 (b) 8000 (c) 80
  17. 17.Best estimate of 665 + 640? (a) 1100 (b) 1500 (c) 1300
  18. 18.Best estimate of 799 + 518? (a) 1100 (b) 1500 (c) 1300
  19. 19.Best estimate of 877 + 709? (a) 1400 (b) 1800 (c) 1600
  20. 20.Best estimate of 33 × 21? (a) 60 (b) 6000 (c) 600
  21. 21.Best estimate of 77 × 23? (a) 16000 (b) 1600 (c) 160
  22. 22.Best estimate of 60 × 81? (a) 480 (b) 48000 (c) 4800
  23. 23.Best estimate of 52 × 86? (a) 450 (b) 45000 (c) 4500
  24. 24.Best estimate of 53 × 52? (a) 250 (b) 2500 (c) 25000
  25. 25.Best estimate of 122 + 133? (a) 200 (b) 400 (c) 0
  26. 26.Best estimate of 302 + 307? (a) 400 (b) 600 (c) 800
  27. 27.Best estimate of 788 + 776? (a) 1600 (b) 1400 (c) 1800
  28. 28.Best estimate of 314 + 761? (a) 1300 (b) 900 (c) 1100
  29. 29.Best estimate of 405 + 675? (a) 900 (b) 1300 (c) 1100
  30. 30.Best estimate of 36 × 73? (a) 2800 (b) 28000 (c) 280
  31. 31.Best estimate of 33 × 33? (a) 90 (b) 900 (c) 9000
  32. 32.Best estimate of 470 + 457? (a) 1000 (b) 1200 (c) 800
  33. 33.Best estimate of 193 + 172? (a) 200 (b) 400 (c) 600
  34. 34.Best estimate of 59 × 66? (a) 4200 (b) 420 (c) 42000
  35. 35.Best estimate of 48 × 46? (a) 250 (b) 2500 (c) 25000
  36. 36.Best estimate of 825 + 191? (a) 1200 (b) 1000 (c) 800
  37. 37.Best estimate of 454 + 284? (a) 1000 (b) 800 (c) 600
  38. 38.Best estimate of 856 + 351? (a) 1300 (b) 1500 (c) 1100
  39. 39.Best estimate of 127 + 287? (a) 400 (b) 200 (c) 600
  40. 40.Best estimate of 68 × 18? (a) 1400 (b) 140 (c) 14000

Answer key

  1. 1800
  2. 1800
  3. 3500
  4. 200
  5. 600
  6. 4500
  7. 300
  8. 3600
  9. 2400
  10. 1100
  11. 400
  12. 900
  13. 1200
  14. 3500
  15. 900
  16. 800
  17. 1300
  18. 1300
  19. 1600
  20. 600
  21. 1600
  22. 4800
  23. 4500
  24. 2500
  25. 200
  26. 600
  27. 1600
  28. 1100
  29. 1100
  30. 2800
  31. 900
  32. 1000
  33. 400
  34. 4200
  35. 2500
  36. 1000
  37. 800
  38. 1300
  39. 400
  40. 1400

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