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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 150 · 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 14 × 43? (a) 4000 (b) 40 (c) 400
  2. 2.Best estimate of 190 + 349? (a) 500 (b) 300 (c) 700
  3. 3.Best estimate of 37 × 53? (a) 2000 (b) 20000 (c) 200
  4. 4.Best estimate of 26 × 31? (a) 90 (b) 9000 (c) 900
  5. 5.Best estimate of 154 + 379? (a) 800 (b) 400 (c) 600
  6. 6.Best estimate of 175 + 661? (a) 700 (b) 900 (c) 1100
  7. 7.Best estimate of 96 × 40? (a) 400 (b) 4000 (c) 40000
  8. 8.Best estimate of 22 × 69? (a) 1400 (b) 14000 (c) 140
  9. 9.Best estimate of 74 × 68? (a) 49000 (b) 4900 (c) 490
  10. 10.Best estimate of 30 × 26? (a) 9000 (b) 900 (c) 90
  11. 11.Best estimate of 64 × 54? (a) 3000 (b) 300 (c) 30000
  12. 12.Best estimate of 616 + 332? (a) 900 (b) 1100 (c) 700
  13. 13.Best estimate of 66 × 77? (a) 56000 (b) 560 (c) 5600
  14. 14.Best estimate of 12 × 37? (a) 40 (b) 400 (c) 4000
  15. 15.Best estimate of 873 + 839? (a) 1900 (b) 1700 (c) 1500
  16. 16.Best estimate of 87 × 74? (a) 6300 (b) 630 (c) 63000
  17. 17.Best estimate of 76 × 94? (a) 720 (b) 72000 (c) 7200
  18. 18.Best estimate of 319 + 160? (a) 500 (b) 700 (c) 300
  19. 19.Best estimate of 44 × 36? (a) 160 (b) 1600 (c) 16000
  20. 20.Best estimate of 79 × 29? (a) 24000 (b) 2400 (c) 240
  21. 21.Best estimate of 588 + 482? (a) 1300 (b) 900 (c) 1100
  22. 22.Best estimate of 388 + 331? (a) 500 (b) 900 (c) 700
  23. 23.Best estimate of 848 + 279? (a) 1100 (b) 1300 (c) 900
  24. 24.Best estimate of 30 × 88? (a) 27000 (b) 270 (c) 2700
  25. 25.Best estimate of 491 + 513? (a) 1200 (b) 1000 (c) 800
  26. 26.Best estimate of 759 + 841? (a) 1600 (b) 1400 (c) 1800
  27. 27.Best estimate of 38 × 57? (a) 24000 (b) 240 (c) 2400
  28. 28.Best estimate of 91 × 21? (a) 18000 (b) 180 (c) 1800
  29. 29.Best estimate of 98 × 41? (a) 400 (b) 4000 (c) 40000
  30. 30.Best estimate of 24 × 26? (a) 6000 (b) 60 (c) 600
  31. 31.Best estimate of 356 + 533? (a) 1100 (b) 700 (c) 900
  32. 32.Best estimate of 26 × 78? (a) 2400 (b) 240 (c) 24000
  33. 33.Best estimate of 225 + 190? (a) 200 (b) 400 (c) 600
  34. 34.Best estimate of 773 + 160? (a) 1000 (b) 1200 (c) 800
  35. 35.Best estimate of 86 × 57? (a) 54000 (b) 5400 (c) 540
  36. 36.Best estimate of 726 + 247? (a) 900 (b) 700 (c) 1100
  37. 37.Best estimate of 36 × 82? (a) 32000 (b) 3200 (c) 320
  38. 38.Best estimate of 801 + 720? (a) 1700 (b) 1300 (c) 1500
  39. 39.Best estimate of 38 × 67? (a) 2800 (b) 280 (c) 28000
  40. 40.Best estimate of 582 + 181? (a) 800 (b) 600 (c) 1000

Answer key

  1. 400
  2. 500
  3. 2000
  4. 900
  5. 600
  6. 900
  7. 4000
  8. 1400
  9. 4900
  10. 900
  11. 3000
  12. 900
  13. 5600
  14. 400
  15. 1700
  16. 6300
  17. 7200
  18. 500
  19. 1600
  20. 2400
  21. 1100
  22. 700
  23. 1100
  24. 2700
  25. 1000
  26. 1600
  27. 2400
  28. 1800
  29. 4000
  30. 600
  31. 900
  32. 2400
  33. 400
  34. 1000
  35. 5400
  36. 900
  37. 3200
  38. 1500
  39. 2800
  40. 800

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