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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 966 · 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 645 + 154? (a) 600 (b) 1000 (c) 800
  2. 2.Best estimate of 76 × 32? (a) 24000 (b) 240 (c) 2400
  3. 3.Best estimate of 80 × 44? (a) 3200 (b) 32000 (c) 320
  4. 4.Best estimate of 68 × 21? (a) 14000 (b) 140 (c) 1400
  5. 5.Best estimate of 870 + 285? (a) 1200 (b) 1000 (c) 1400
  6. 6.Best estimate of 13 × 96? (a) 10000 (b) 1000 (c) 100
  7. 7.Best estimate of 185 + 824? (a) 800 (b) 1000 (c) 1200
  8. 8.Best estimate of 76 × 91? (a) 720 (b) 7200 (c) 72000
  9. 9.Best estimate of 72 × 27? (a) 2100 (b) 210 (c) 21000
  10. 10.Best estimate of 339 + 629? (a) 900 (b) 1100 (c) 700
  11. 11.Best estimate of 56 × 92? (a) 540 (b) 5400 (c) 54000
  12. 12.Best estimate of 87 × 97? (a) 90000 (b) 900 (c) 9000
  13. 13.Best estimate of 93 × 68? (a) 6300 (b) 630 (c) 63000
  14. 14.Best estimate of 753 + 491? (a) 1300 (b) 1500 (c) 1100
  15. 15.Best estimate of 12 × 37? (a) 4000 (b) 40 (c) 400
  16. 16.Best estimate of 23 × 71? (a) 140 (b) 14000 (c) 1400
  17. 17.Best estimate of 66 × 46? (a) 35000 (b) 350 (c) 3500
  18. 18.Best estimate of 80 × 31? (a) 2400 (b) 240 (c) 24000
  19. 19.Best estimate of 880 + 192? (a) 1100 (b) 900 (c) 1300
  20. 20.Best estimate of 39 × 83? (a) 32000 (b) 3200 (c) 320
  21. 21.Best estimate of 494 + 517? (a) 800 (b) 1200 (c) 1000
  22. 22.Best estimate of 285 + 192? (a) 500 (b) 700 (c) 300
  23. 23.Best estimate of 36 × 92? (a) 36000 (b) 360 (c) 3600
  24. 24.Best estimate of 795 + 176? (a) 1000 (b) 1200 (c) 800
  25. 25.Best estimate of 556 + 865? (a) 1300 (b) 1700 (c) 1500
  26. 26.Best estimate of 631 + 223? (a) 800 (b) 600 (c) 1000
  27. 27.Best estimate of 204 + 158? (a) 200 (b) 400 (c) 600
  28. 28.Best estimate of 53 × 18? (a) 100 (b) 1000 (c) 10000
  29. 29.Best estimate of 68 × 86? (a) 630 (b) 63000 (c) 6300
  30. 30.Best estimate of 40 × 57? (a) 2400 (b) 240 (c) 24000
  31. 31.Best estimate of 41 × 51? (a) 200 (b) 2000 (c) 20000
  32. 32.Best estimate of 21 × 92? (a) 1800 (b) 18000 (c) 180
  33. 33.Best estimate of 748 + 381? (a) 900 (b) 1300 (c) 1100
  34. 34.Best estimate of 54 × 79? (a) 400 (b) 4000 (c) 40000
  35. 35.Best estimate of 323 + 213? (a) 500 (b) 700 (c) 300
  36. 36.Best estimate of 445 + 586? (a) 800 (b) 1000 (c) 1200
  37. 37.Best estimate of 271 + 679? (a) 1000 (b) 800 (c) 1200
  38. 38.Best estimate of 406 + 143? (a) 700 (b) 500 (c) 300
  39. 39.Best estimate of 755 + 527? (a) 1500 (b) 1300 (c) 1100
  40. 40.Best estimate of 334 + 502? (a) 600 (b) 1000 (c) 800

Answer key

  1. 800
  2. 2400
  3. 3200
  4. 1400
  5. 1200
  6. 1000
  7. 1000
  8. 7200
  9. 2100
  10. 900
  11. 5400
  12. 9000
  13. 6300
  14. 1300
  15. 400
  16. 1400
  17. 3500
  18. 2400
  19. 1100
  20. 3200
  21. 1000
  22. 500
  23. 3600
  24. 1000
  25. 1500
  26. 800
  27. 400
  28. 1000
  29. 6300
  30. 2400
  31. 2000
  32. 1800
  33. 1100
  34. 4000
  35. 500
  36. 1000
  37. 1000
  38. 500
  39. 1300
  40. 800

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