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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 168 · 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 58 × 36? (a) 24000 (b) 2400 (c) 240
  2. 2.Best estimate of 76 × 69? (a) 5600 (b) 56000 (c) 560
  3. 3.Best estimate of 361 + 420? (a) 600 (b) 1000 (c) 800
  4. 4.Best estimate of 298 + 867? (a) 1400 (b) 1200 (c) 1000
  5. 5.Best estimate of 53 × 58? (a) 3000 (b) 30000 (c) 300
  6. 6.Best estimate of 43 × 31? (a) 12000 (b) 1200 (c) 120
  7. 7.Best estimate of 836 + 380? (a) 1200 (b) 1000 (c) 1400
  8. 8.Best estimate of 81 × 34? (a) 2400 (b) 24000 (c) 240
  9. 9.Best estimate of 195 + 692? (a) 900 (b) 1100 (c) 700
  10. 10.Best estimate of 331 + 254? (a) 800 (b) 600 (c) 400
  11. 11.Best estimate of 301 + 314? (a) 800 (b) 400 (c) 600
  12. 12.Best estimate of 785 + 828? (a) 1800 (b) 1600 (c) 1400
  13. 13.Best estimate of 64 × 50? (a) 30000 (b) 300 (c) 3000
  14. 14.Best estimate of 71 × 81? (a) 5600 (b) 560 (c) 56000
  15. 15.Best estimate of 384 + 364? (a) 1000 (b) 800 (c) 600
  16. 16.Best estimate of 676 + 796? (a) 1500 (b) 1700 (c) 1300
  17. 17.Best estimate of 458 + 635? (a) 1300 (b) 1100 (c) 900
  18. 18.Best estimate of 17 × 23? (a) 40 (b) 400 (c) 4000
  19. 19.Best estimate of 17 × 36? (a) 80 (b) 8000 (c) 800
  20. 20.Best estimate of 251 + 589? (a) 1100 (b) 700 (c) 900
  21. 21.Best estimate of 66 × 77? (a) 56000 (b) 5600 (c) 560
  22. 22.Best estimate of 46 × 92? (a) 45000 (b) 4500 (c) 450
  23. 23.Best estimate of 391 + 283? (a) 900 (b) 500 (c) 700
  24. 24.Best estimate of 57 × 64? (a) 3600 (b) 360 (c) 36000
  25. 25.Best estimate of 128 + 452? (a) 800 (b) 600 (c) 400
  26. 26.Best estimate of 61 × 60? (a) 360 (b) 3600 (c) 36000
  27. 27.Best estimate of 864 + 672? (a) 1400 (b) 1800 (c) 1600
  28. 28.Best estimate of 37 × 93? (a) 3600 (b) 36000 (c) 360
  29. 29.Best estimate of 20 × 36? (a) 80 (b) 8000 (c) 800
  30. 30.Best estimate of 23 × 27? (a) 60 (b) 6000 (c) 600
  31. 31.Best estimate of 23 × 52? (a) 1000 (b) 10000 (c) 100
  32. 32.Best estimate of 61 × 97? (a) 60000 (b) 6000 (c) 600
  33. 33.Best estimate of 46 × 17? (a) 1000 (b) 100 (c) 10000
  34. 34.Best estimate of 94 × 39? (a) 3600 (b) 36000 (c) 360
  35. 35.Best estimate of 49 × 34? (a) 1500 (b) 15000 (c) 150
  36. 36.Best estimate of 86 × 38? (a) 36000 (b) 360 (c) 3600
  37. 37.Best estimate of 78 × 69? (a) 56000 (b) 5600 (c) 560
  38. 38.Best estimate of 97 × 21? (a) 200 (b) 2000 (c) 20000
  39. 39.Best estimate of 824 + 349? (a) 900 (b) 1100 (c) 1300
  40. 40.Best estimate of 558 + 280? (a) 900 (b) 700 (c) 1100

Answer key

  1. 2400
  2. 5600
  3. 800
  4. 1200
  5. 3000
  6. 1200
  7. 1200
  8. 2400
  9. 900
  10. 600
  11. 600
  12. 1600
  13. 3000
  14. 5600
  15. 800
  16. 1500
  17. 1100
  18. 400
  19. 800
  20. 900
  21. 5600
  22. 4500
  23. 700
  24. 3600
  25. 600
  26. 3600
  27. 1600
  28. 3600
  29. 800
  30. 600
  31. 1000
  32. 6000
  33. 1000
  34. 3600
  35. 1500
  36. 3600
  37. 5600
  38. 2000
  39. 1100
  40. 900

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