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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 877 · 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 77 × 40? (a) 3200 (b) 32000 (c) 320
  2. 2.Best estimate of 19 × 18? (a) 400 (b) 40 (c) 4000
  3. 3.Best estimate of 23 × 60? (a) 120 (b) 12000 (c) 1200
  4. 4.Best estimate of 356 + 277? (a) 700 (b) 900 (c) 500
  5. 5.Best estimate of 596 + 847? (a) 1200 (b) 1600 (c) 1400
  6. 6.Best estimate of 44 × 56? (a) 240 (b) 24000 (c) 2400
  7. 7.Best estimate of 62 × 36? (a) 24000 (b) 240 (c) 2400
  8. 8.Best estimate of 759 + 871? (a) 1700 (b) 1900 (c) 1500
  9. 9.Best estimate of 646 + 790? (a) 1400 (b) 1600 (c) 1200
  10. 10.Best estimate of 76 × 32? (a) 2400 (b) 24000 (c) 240
  11. 11.Best estimate of 58 × 46? (a) 3000 (b) 30000 (c) 300
  12. 12.Best estimate of 199 + 277? (a) 500 (b) 300 (c) 700
  13. 13.Best estimate of 499 + 654? (a) 1400 (b) 1000 (c) 1200
  14. 14.Best estimate of 22 × 21? (a) 40 (b) 4000 (c) 400
  15. 15.Best estimate of 28 × 78? (a) 24000 (b) 2400 (c) 240
  16. 16.Best estimate of 410 + 136? (a) 500 (b) 700 (c) 300
  17. 17.Best estimate of 69 × 60? (a) 420 (b) 42000 (c) 4200
  18. 18.Best estimate of 18 × 74? (a) 1400 (b) 140 (c) 14000
  19. 19.Best estimate of 512 + 413? (a) 1100 (b) 700 (c) 900
  20. 20.Best estimate of 16 × 66? (a) 14000 (b) 140 (c) 1400
  21. 21.Best estimate of 196 + 388? (a) 800 (b) 400 (c) 600
  22. 22.Best estimate of 538 + 332? (a) 800 (b) 1000 (c) 600
  23. 23.Best estimate of 507 + 447? (a) 900 (b) 700 (c) 1100
  24. 24.Best estimate of 432 + 571? (a) 1000 (b) 1200 (c) 800
  25. 25.Best estimate of 289 + 519? (a) 1000 (b) 600 (c) 800
  26. 26.Best estimate of 21 × 22? (a) 4000 (b) 400 (c) 40
  27. 27.Best estimate of 47 × 87? (a) 4500 (b) 45000 (c) 450
  28. 28.Best estimate of 83 × 89? (a) 72000 (b) 720 (c) 7200
  29. 29.Best estimate of 501 + 247? (a) 500 (b) 900 (c) 700
  30. 30.Best estimate of 78 × 16? (a) 160 (b) 16000 (c) 1600
  31. 31.Best estimate of 661 + 577? (a) 1500 (b) 1300 (c) 1100
  32. 32.Best estimate of 19 × 50? (a) 100 (b) 1000 (c) 10000
  33. 33.Best estimate of 343 + 708? (a) 1000 (b) 800 (c) 1200
  34. 34.Best estimate of 98 × 23? (a) 2000 (b) 20000 (c) 200
  35. 35.Best estimate of 827 + 734? (a) 1500 (b) 1700 (c) 1300
  36. 36.Best estimate of 90 × 36? (a) 360 (b) 3600 (c) 36000
  37. 37.Best estimate of 291 + 175? (a) 700 (b) 500 (c) 300
  38. 38.Best estimate of 34 × 27? (a) 90 (b) 9000 (c) 900
  39. 39.Best estimate of 88 × 12? (a) 9000 (b) 900 (c) 90
  40. 40.Best estimate of 764 + 682? (a) 1300 (b) 1700 (c) 1500

Answer key

  1. 3200
  2. 400
  3. 1200
  4. 700
  5. 1400
  6. 2400
  7. 2400
  8. 1700
  9. 1400
  10. 2400
  11. 3000
  12. 500
  13. 1200
  14. 400
  15. 2400
  16. 500
  17. 4200
  18. 1400
  19. 900
  20. 1400
  21. 600
  22. 800
  23. 900
  24. 1000
  25. 800
  26. 400
  27. 4500
  28. 7200
  29. 700
  30. 1600
  31. 1300
  32. 1000
  33. 1000
  34. 2000
  35. 1500
  36. 3600
  37. 500
  38. 900
  39. 900
  40. 1500

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