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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 219 · 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 168 + 214? (a) 400 (b) 200 (c) 600
  2. 2.Best estimate of 20 × 96? (a) 200 (b) 2000 (c) 20000
  3. 3.Best estimate of 71 × 87? (a) 6300 (b) 63000 (c) 630
  4. 4.Best estimate of 491 + 299? (a) 1000 (b) 600 (c) 800
  5. 5.Best estimate of 33 × 12? (a) 300 (b) 3000 (c) 30
  6. 6.Best estimate of 53 × 88? (a) 4500 (b) 450 (c) 45000
  7. 7.Best estimate of 59 × 23? (a) 120 (b) 12000 (c) 1200
  8. 8.Best estimate of 152 + 587? (a) 600 (b) 1000 (c) 800
  9. 9.Best estimate of 58 × 88? (a) 54000 (b) 540 (c) 5400
  10. 10.Best estimate of 86 × 18? (a) 1800 (b) 180 (c) 18000
  11. 11.Best estimate of 81 × 64? (a) 48000 (b) 4800 (c) 480
  12. 12.Best estimate of 336 + 724? (a) 1000 (b) 800 (c) 1200
  13. 13.Best estimate of 36 × 68? (a) 280 (b) 2800 (c) 28000
  14. 14.Best estimate of 82 × 86? (a) 7200 (b) 720 (c) 72000
  15. 15.Best estimate of 573 + 476? (a) 1300 (b) 900 (c) 1100
  16. 16.Best estimate of 875 + 525? (a) 1600 (b) 1400 (c) 1200
  17. 17.Best estimate of 48 × 16? (a) 10000 (b) 100 (c) 1000
  18. 18.Best estimate of 19 × 27? (a) 60 (b) 600 (c) 6000
  19. 19.Best estimate of 237 + 305? (a) 700 (b) 500 (c) 300
  20. 20.Best estimate of 63 × 14? (a) 6000 (b) 60 (c) 600
  21. 21.Best estimate of 844 + 260? (a) 1100 (b) 1300 (c) 900
  22. 22.Best estimate of 13 × 36? (a) 400 (b) 4000 (c) 40
  23. 23.Best estimate of 71 × 68? (a) 49000 (b) 4900 (c) 490
  24. 24.Best estimate of 62 × 16? (a) 12000 (b) 1200 (c) 120
  25. 25.Best estimate of 81 × 61? (a) 4800 (b) 48000 (c) 480
  26. 26.Best estimate of 29 × 61? (a) 1800 (b) 180 (c) 18000
  27. 27.Best estimate of 251 + 565? (a) 1100 (b) 900 (c) 700
  28. 28.Best estimate of 451 + 232? (a) 900 (b) 500 (c) 700
  29. 29.Best estimate of 161 + 167? (a) 200 (b) 600 (c) 400
  30. 30.Best estimate of 33 × 28? (a) 9000 (b) 900 (c) 90
  31. 31.Best estimate of 403 + 822? (a) 1400 (b) 1000 (c) 1200
  32. 32.Best estimate of 36 × 17? (a) 80 (b) 800 (c) 8000
  33. 33.Best estimate of 226 + 301? (a) 700 (b) 500 (c) 300
  34. 34.Best estimate of 682 + 413? (a) 1100 (b) 900 (c) 1300
  35. 35.Best estimate of 12 × 18? (a) 20 (b) 200 (c) 2000
  36. 36.Best estimate of 18 × 68? (a) 14000 (b) 140 (c) 1400
  37. 37.Best estimate of 851 + 183? (a) 1300 (b) 900 (c) 1100
  38. 38.Best estimate of 852 + 724? (a) 1800 (b) 1400 (c) 1600
  39. 39.Best estimate of 582 + 254? (a) 700 (b) 1100 (c) 900
  40. 40.Best estimate of 93 × 23? (a) 1800 (b) 180 (c) 18000

Answer key

  1. 400
  2. 2000
  3. 6300
  4. 800
  5. 300
  6. 4500
  7. 1200
  8. 800
  9. 5400
  10. 1800
  11. 4800
  12. 1000
  13. 2800
  14. 7200
  15. 1100
  16. 1400
  17. 1000
  18. 600
  19. 500
  20. 600
  21. 1100
  22. 400
  23. 4900
  24. 1200
  25. 4800
  26. 1800
  27. 900
  28. 700
  29. 400
  30. 900
  31. 1200
  32. 800
  33. 500
  34. 1100
  35. 200
  36. 1400
  37. 1100
  38. 1600
  39. 900
  40. 1800

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