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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 942 · 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 624 + 347? (a) 700 (b) 1100 (c) 900
  2. 2.Best estimate of 52 × 62? (a) 300 (b) 3000 (c) 30000
  3. 3.Best estimate of 800 + 264? (a) 1300 (b) 1100 (c) 900
  4. 4.Best estimate of 31 × 39? (a) 1200 (b) 120 (c) 12000
  5. 5.Best estimate of 723 + 622? (a) 1500 (b) 1100 (c) 1300
  6. 6.Best estimate of 94 × 56? (a) 5400 (b) 540 (c) 54000
  7. 7.Best estimate of 830 + 364? (a) 1400 (b) 1000 (c) 1200
  8. 8.Best estimate of 98 × 12? (a) 1000 (b) 10000 (c) 100
  9. 9.Best estimate of 73 × 66? (a) 49000 (b) 490 (c) 4900
  10. 10.Best estimate of 225 + 529? (a) 700 (b) 900 (c) 500
  11. 11.Best estimate of 18 × 70? (a) 14000 (b) 140 (c) 1400
  12. 12.Best estimate of 63 × 21? (a) 12000 (b) 120 (c) 1200
  13. 13.Best estimate of 76 × 66? (a) 56000 (b) 5600 (c) 560
  14. 14.Best estimate of 201 + 630? (a) 1000 (b) 800 (c) 600
  15. 15.Best estimate of 470 + 406? (a) 1100 (b) 700 (c) 900
  16. 16.Best estimate of 83 × 61? (a) 480 (b) 4800 (c) 48000
  17. 17.Best estimate of 41 × 59? (a) 24000 (b) 240 (c) 2400
  18. 18.Best estimate of 30 × 56? (a) 1800 (b) 180 (c) 18000
  19. 19.Best estimate of 186 + 468? (a) 500 (b) 700 (c) 900
  20. 20.Best estimate of 59 × 37? (a) 24000 (b) 2400 (c) 240
  21. 21.Best estimate of 72 × 76? (a) 560 (b) 5600 (c) 56000
  22. 22.Best estimate of 62 × 31? (a) 180 (b) 1800 (c) 18000
  23. 23.Best estimate of 794 + 126? (a) 700 (b) 900 (c) 1100
  24. 24.Best estimate of 19 × 20? (a) 400 (b) 4000 (c) 40
  25. 25.Best estimate of 47 × 94? (a) 4500 (b) 450 (c) 45000
  26. 26.Best estimate of 73 × 27? (a) 21000 (b) 2100 (c) 210
  27. 27.Best estimate of 93 × 86? (a) 810 (b) 8100 (c) 81000
  28. 28.Best estimate of 867 + 337? (a) 1200 (b) 1000 (c) 1400
  29. 29.Best estimate of 325 + 180? (a) 700 (b) 500 (c) 300
  30. 30.Best estimate of 86 × 72? (a) 630 (b) 63000 (c) 6300
  31. 31.Best estimate of 34 × 94? (a) 27000 (b) 2700 (c) 270
  32. 32.Best estimate of 790 + 248? (a) 1200 (b) 800 (c) 1000
  33. 33.Best estimate of 57 × 36? (a) 2400 (b) 240 (c) 24000
  34. 34.Best estimate of 193 + 803? (a) 800 (b) 1200 (c) 1000
  35. 35.Best estimate of 89 × 17? (a) 1800 (b) 18000 (c) 180
  36. 36.Best estimate of 138 + 876? (a) 1200 (b) 1000 (c) 800
  37. 37.Best estimate of 831 + 427? (a) 1400 (b) 1000 (c) 1200
  38. 38.Best estimate of 96 × 12? (a) 10000 (b) 1000 (c) 100
  39. 39.Best estimate of 20 × 43? (a) 8000 (b) 800 (c) 80
  40. 40.Best estimate of 67 × 90? (a) 63000 (b) 6300 (c) 630

Answer key

  1. 900
  2. 3000
  3. 1100
  4. 1200
  5. 1300
  6. 5400
  7. 1200
  8. 1000
  9. 4900
  10. 700
  11. 1400
  12. 1200
  13. 5600
  14. 800
  15. 900
  16. 4800
  17. 2400
  18. 1800
  19. 700
  20. 2400
  21. 5600
  22. 1800
  23. 900
  24. 400
  25. 4500
  26. 2100
  27. 8100
  28. 1200
  29. 500
  30. 6300
  31. 2700
  32. 1000
  33. 2400
  34. 1000
  35. 1800
  36. 1000
  37. 1200
  38. 1000
  39. 800
  40. 6300

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