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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 365 · 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 14 × 83? (a) 80 (b) 8000 (c) 800
  2. 2.Best estimate of 83 × 49? (a) 40000 (b) 400 (c) 4000
  3. 3.Best estimate of 47 × 12? (a) 50 (b) 5000 (c) 500
  4. 4.Best estimate of 661 + 265? (a) 1000 (b) 800 (c) 1200
  5. 5.Best estimate of 315 + 615? (a) 1100 (b) 900 (c) 700
  6. 6.Best estimate of 206 + 342? (a) 700 (b) 500 (c) 300
  7. 7.Best estimate of 687 + 562? (a) 1500 (b) 1300 (c) 1100
  8. 8.Best estimate of 66 × 76? (a) 560 (b) 5600 (c) 56000
  9. 9.Best estimate of 76 × 12? (a) 8000 (b) 80 (c) 800
  10. 10.Best estimate of 22 × 77? (a) 16000 (b) 1600 (c) 160
  11. 11.Best estimate of 54 × 50? (a) 2500 (b) 250 (c) 25000
  12. 12.Best estimate of 176 + 220? (a) 600 (b) 400 (c) 200
  13. 13.Best estimate of 187 + 529? (a) 700 (b) 500 (c) 900
  14. 14.Best estimate of 16 × 42? (a) 80 (b) 8000 (c) 800
  15. 15.Best estimate of 654 + 686? (a) 1600 (b) 1200 (c) 1400
  16. 16.Best estimate of 46 × 82? (a) 400 (b) 40000 (c) 4000
  17. 17.Best estimate of 773 + 421? (a) 1200 (b) 1400 (c) 1000
  18. 18.Best estimate of 62 × 34? (a) 18000 (b) 180 (c) 1800
  19. 19.Best estimate of 61 × 61? (a) 360 (b) 3600 (c) 36000
  20. 20.Best estimate of 26 × 76? (a) 240 (b) 24000 (c) 2400
  21. 21.Best estimate of 391 + 495? (a) 900 (b) 1100 (c) 700
  22. 22.Best estimate of 61 × 70? (a) 4200 (b) 42000 (c) 420
  23. 23.Best estimate of 748 + 740? (a) 1200 (b) 1600 (c) 1400
  24. 24.Best estimate of 768 + 772? (a) 1600 (b) 1800 (c) 1400
  25. 25.Best estimate of 340 + 186? (a) 300 (b) 500 (c) 700
  26. 26.Best estimate of 46 × 26? (a) 150 (b) 15000 (c) 1500
  27. 27.Best estimate of 31 × 96? (a) 300 (b) 30000 (c) 3000
  28. 28.Best estimate of 90 × 94? (a) 810 (b) 81000 (c) 8100
  29. 29.Best estimate of 37 × 73? (a) 2800 (b) 28000 (c) 280
  30. 30.Best estimate of 12 × 31? (a) 300 (b) 30 (c) 3000
  31. 31.Best estimate of 41 × 32? (a) 12000 (b) 120 (c) 1200
  32. 32.Best estimate of 90 × 66? (a) 6300 (b) 630 (c) 63000
  33. 33.Best estimate of 81 × 78? (a) 6400 (b) 64000 (c) 640
  34. 34.Best estimate of 81 × 60? (a) 480 (b) 48000 (c) 4800
  35. 35.Best estimate of 607 + 251? (a) 900 (b) 700 (c) 1100
  36. 36.Best estimate of 48 × 84? (a) 4000 (b) 40000 (c) 400
  37. 37.Best estimate of 637 + 823? (a) 1600 (b) 1400 (c) 1200
  38. 38.Best estimate of 511 + 429? (a) 1100 (b) 900 (c) 700
  39. 39.Best estimate of 396 + 858? (a) 1500 (b) 1100 (c) 1300
  40. 40.Best estimate of 26 × 40? (a) 1200 (b) 12000 (c) 120

Answer key

  1. 800
  2. 4000
  3. 500
  4. 1000
  5. 900
  6. 500
  7. 1300
  8. 5600
  9. 800
  10. 1600
  11. 2500
  12. 400
  13. 700
  14. 800
  15. 1400
  16. 4000
  17. 1200
  18. 1800
  19. 3600
  20. 2400
  21. 900
  22. 4200
  23. 1400
  24. 1600
  25. 500
  26. 1500
  27. 3000
  28. 8100
  29. 2800
  30. 300
  31. 1200
  32. 6300
  33. 6400
  34. 4800
  35. 900
  36. 4000
  37. 1400
  38. 900
  39. 1300
  40. 1200

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