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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 313 · 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 629 + 354? (a) 1000 (b) 800 (c) 1200
  2. 2.Best estimate of 84 × 33? (a) 2400 (b) 24000 (c) 240
  3. 3.Best estimate of 239 + 351? (a) 600 (b) 800 (c) 400
  4. 4.Best estimate of 72 × 82? (a) 56000 (b) 5600 (c) 560
  5. 5.Best estimate of 379 + 242? (a) 800 (b) 600 (c) 400
  6. 6.Best estimate of 88 × 46? (a) 45000 (b) 450 (c) 4500
  7. 7.Best estimate of 606 + 845? (a) 1600 (b) 1200 (c) 1400
  8. 8.Best estimate of 371 + 311? (a) 700 (b) 500 (c) 900
  9. 9.Best estimate of 21 × 92? (a) 1800 (b) 18000 (c) 180
  10. 10.Best estimate of 94 × 58? (a) 54000 (b) 5400 (c) 540
  11. 11.Best estimate of 154 + 558? (a) 1000 (b) 800 (c) 600
  12. 12.Best estimate of 72 × 60? (a) 420 (b) 4200 (c) 42000
  13. 13.Best estimate of 566 + 520? (a) 1100 (b) 1300 (c) 900
  14. 14.Best estimate of 70 × 93? (a) 630 (b) 63000 (c) 6300
  15. 15.Best estimate of 96 × 96? (a) 1000 (b) 100000 (c) 10000
  16. 16.Best estimate of 86 × 92? (a) 81000 (b) 8100 (c) 810
  17. 17.Best estimate of 683 + 379? (a) 1100 (b) 1300 (c) 900
  18. 18.Best estimate of 198 + 498? (a) 700 (b) 900 (c) 500
  19. 19.Best estimate of 743 + 769? (a) 1700 (b) 1300 (c) 1500
  20. 20.Best estimate of 320 + 231? (a) 700 (b) 500 (c) 300
  21. 21.Best estimate of 251 + 390? (a) 700 (b) 900 (c) 500
  22. 22.Best estimate of 32 × 28? (a) 90 (b) 9000 (c) 900
  23. 23.Best estimate of 31 × 26? (a) 90 (b) 900 (c) 9000
  24. 24.Best estimate of 46 × 52? (a) 2500 (b) 250 (c) 25000
  25. 25.Best estimate of 91 × 43? (a) 36000 (b) 3600 (c) 360
  26. 26.Best estimate of 28 × 56? (a) 18000 (b) 180 (c) 1800
  27. 27.Best estimate of 89 × 91? (a) 81000 (b) 810 (c) 8100
  28. 28.Best estimate of 403 + 306? (a) 700 (b) 500 (c) 900
  29. 29.Best estimate of 757 + 671? (a) 1300 (b) 1700 (c) 1500
  30. 30.Best estimate of 610 + 695? (a) 1500 (b) 1100 (c) 1300
  31. 31.Best estimate of 88 × 40? (a) 3600 (b) 36000 (c) 360
  32. 32.Best estimate of 31 × 16? (a) 600 (b) 60 (c) 6000
  33. 33.Best estimate of 40 × 52? (a) 20000 (b) 200 (c) 2000
  34. 34.Best estimate of 83 × 54? (a) 400 (b) 40000 (c) 4000
  35. 35.Best estimate of 96 × 14? (a) 10000 (b) 1000 (c) 100
  36. 36.Best estimate of 663 + 372? (a) 1300 (b) 1100 (c) 900
  37. 37.Best estimate of 18 × 26? (a) 60 (b) 6000 (c) 600
  38. 38.Best estimate of 23 × 57? (a) 12000 (b) 1200 (c) 120
  39. 39.Best estimate of 403 + 598? (a) 800 (b) 1200 (c) 1000
  40. 40.Best estimate of 88 × 74? (a) 63000 (b) 630 (c) 6300

Answer key

  1. 1000
  2. 2400
  3. 600
  4. 5600
  5. 600
  6. 4500
  7. 1400
  8. 700
  9. 1800
  10. 5400
  11. 800
  12. 4200
  13. 1100
  14. 6300
  15. 10000
  16. 8100
  17. 1100
  18. 700
  19. 1500
  20. 500
  21. 700
  22. 900
  23. 900
  24. 2500
  25. 3600
  26. 1800
  27. 8100
  28. 700
  29. 1500
  30. 1300
  31. 3600
  32. 600
  33. 2000
  34. 4000
  35. 1000
  36. 1100
  37. 600
  38. 1200
  39. 1000
  40. 6300

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