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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 719 · 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 47 × 36? (a) 2000 (b) 200 (c) 20000
  2. 2.Best estimate of 679 + 126? (a) 800 (b) 1000 (c) 600
  3. 3.Best estimate of 416 + 148? (a) 500 (b) 700 (c) 300
  4. 4.Best estimate of 47 × 21? (a) 10000 (b) 1000 (c) 100
  5. 5.Best estimate of 88 × 30? (a) 270 (b) 2700 (c) 27000
  6. 6.Best estimate of 36 × 26? (a) 1200 (b) 120 (c) 12000
  7. 7.Best estimate of 30 × 33? (a) 900 (b) 9000 (c) 90
  8. 8.Best estimate of 91 × 26? (a) 2700 (b) 27000 (c) 270
  9. 9.Best estimate of 36 × 87? (a) 3600 (b) 360 (c) 36000
  10. 10.Best estimate of 265 + 658? (a) 1000 (b) 800 (c) 1200
  11. 11.Best estimate of 624 + 620? (a) 1200 (b) 1000 (c) 1400
  12. 12.Best estimate of 645 + 216? (a) 800 (b) 600 (c) 1000
  13. 13.Best estimate of 18 × 16? (a) 4000 (b) 400 (c) 40
  14. 14.Best estimate of 524 + 313? (a) 1000 (b) 600 (c) 800
  15. 15.Best estimate of 66 × 88? (a) 6300 (b) 630 (c) 63000
  16. 16.Best estimate of 414 + 437? (a) 800 (b) 600 (c) 1000
  17. 17.Best estimate of 68 × 12? (a) 700 (b) 7000 (c) 70
  18. 18.Best estimate of 21 × 90? (a) 18000 (b) 180 (c) 1800
  19. 19.Best estimate of 66 × 78? (a) 56000 (b) 560 (c) 5600
  20. 20.Best estimate of 31 × 21? (a) 600 (b) 60 (c) 6000
  21. 21.Best estimate of 797 + 622? (a) 1400 (b) 1200 (c) 1600
  22. 22.Best estimate of 24 × 23? (a) 40 (b) 400 (c) 4000
  23. 23.Best estimate of 316 + 183? (a) 700 (b) 300 (c) 500
  24. 24.Best estimate of 64 × 16? (a) 12000 (b) 120 (c) 1200
  25. 25.Best estimate of 252 + 127? (a) 400 (b) 600 (c) 200
  26. 26.Best estimate of 398 + 741? (a) 900 (b) 1100 (c) 1300
  27. 27.Best estimate of 272 + 797? (a) 1300 (b) 900 (c) 1100
  28. 28.Best estimate of 33 × 71? (a) 2100 (b) 210 (c) 21000
  29. 29.Best estimate of 63 × 41? (a) 24000 (b) 240 (c) 2400
  30. 30.Best estimate of 83 × 36? (a) 320 (b) 32000 (c) 3200
  31. 31.Best estimate of 31 × 29? (a) 90 (b) 9000 (c) 900
  32. 32.Best estimate of 23 × 17? (a) 4000 (b) 40 (c) 400
  33. 33.Best estimate of 800 + 266? (a) 1100 (b) 1300 (c) 900
  34. 34.Best estimate of 772 + 493? (a) 1100 (b) 1300 (c) 1500
  35. 35.Best estimate of 82 × 81? (a) 64000 (b) 6400 (c) 640
  36. 36.Best estimate of 97 × 13? (a) 1000 (b) 100 (c) 10000
  37. 37.Best estimate of 740 + 732? (a) 1200 (b) 1400 (c) 1600
  38. 38.Best estimate of 584 + 160? (a) 600 (b) 1000 (c) 800
  39. 39.Best estimate of 368 + 721? (a) 1100 (b) 1300 (c) 900
  40. 40.Best estimate of 28 × 91? (a) 27000 (b) 270 (c) 2700

Answer key

  1. 2000
  2. 800
  3. 500
  4. 1000
  5. 2700
  6. 1200
  7. 900
  8. 2700
  9. 3600
  10. 1000
  11. 1200
  12. 800
  13. 400
  14. 800
  15. 6300
  16. 800
  17. 700
  18. 1800
  19. 5600
  20. 600
  21. 1400
  22. 400
  23. 500
  24. 1200
  25. 400
  26. 1100
  27. 1100
  28. 2100
  29. 2400
  30. 3200
  31. 900
  32. 400
  33. 1100
  34. 1300
  35. 6400
  36. 1000
  37. 1400
  38. 800
  39. 1100
  40. 2700

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