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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 678 · 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 292 + 253? (a) 400 (b) 600 (c) 800
  2. 2.Best estimate of 36 × 24? (a) 80 (b) 800 (c) 8000
  3. 3.Best estimate of 40 × 68? (a) 2800 (b) 280 (c) 28000
  4. 4.Best estimate of 388 + 265? (a) 700 (b) 900 (c) 500
  5. 5.Best estimate of 399 + 341? (a) 700 (b) 500 (c) 900
  6. 6.Best estimate of 155 + 613? (a) 1000 (b) 600 (c) 800
  7. 7.Best estimate of 167 + 429? (a) 600 (b) 800 (c) 400
  8. 8.Best estimate of 54 × 54? (a) 2500 (b) 25000 (c) 250
  9. 9.Best estimate of 32 × 43? (a) 12000 (b) 120 (c) 1200
  10. 10.Best estimate of 479 + 458? (a) 1000 (b) 800 (c) 1200
  11. 11.Best estimate of 255 + 717? (a) 1000 (b) 1200 (c) 800
  12. 12.Best estimate of 40 × 50? (a) 200 (b) 20000 (c) 2000
  13. 13.Best estimate of 22 × 47? (a) 10000 (b) 1000 (c) 100
  14. 14.Best estimate of 80 × 72? (a) 560 (b) 5600 (c) 56000
  15. 15.Best estimate of 89 × 36? (a) 36000 (b) 360 (c) 3600
  16. 16.Best estimate of 187 + 510? (a) 700 (b) 900 (c) 500
  17. 17.Best estimate of 57 × 96? (a) 6000 (b) 600 (c) 60000
  18. 18.Best estimate of 626 + 548? (a) 1100 (b) 900 (c) 1300
  19. 19.Best estimate of 16 × 87? (a) 180 (b) 1800 (c) 18000
  20. 20.Best estimate of 600 + 377? (a) 1000 (b) 800 (c) 1200
  21. 21.Best estimate of 34 × 58? (a) 1800 (b) 180 (c) 18000
  22. 22.Best estimate of 734 + 392? (a) 1100 (b) 900 (c) 1300
  23. 23.Best estimate of 82 × 16? (a) 160 (b) 16000 (c) 1600
  24. 24.Best estimate of 634 + 259? (a) 900 (b) 700 (c) 1100
  25. 25.Best estimate of 154 + 191? (a) 400 (b) 600 (c) 200
  26. 26.Best estimate of 515 + 470? (a) 1200 (b) 1000 (c) 800
  27. 27.Best estimate of 21 × 54? (a) 10000 (b) 1000 (c) 100
  28. 28.Best estimate of 43 × 89? (a) 36000 (b) 360 (c) 3600
  29. 29.Best estimate of 135 + 735? (a) 800 (b) 600 (c) 1000
  30. 30.Best estimate of 16 × 29? (a) 600 (b) 6000 (c) 60
  31. 31.Best estimate of 620 + 742? (a) 1500 (b) 1100 (c) 1300
  32. 32.Best estimate of 41 × 64? (a) 2400 (b) 24000 (c) 240
  33. 33.Best estimate of 83 × 37? (a) 320 (b) 3200 (c) 32000
  34. 34.Best estimate of 13 × 84? (a) 800 (b) 80 (c) 8000
  35. 35.Best estimate of 16 × 97? (a) 200 (b) 2000 (c) 20000
  36. 36.Best estimate of 76 × 20? (a) 16000 (b) 1600 (c) 160
  37. 37.Best estimate of 225 + 714? (a) 1100 (b) 700 (c) 900
  38. 38.Best estimate of 47 × 12? (a) 500 (b) 50 (c) 5000
  39. 39.Best estimate of 387 + 298? (a) 900 (b) 500 (c) 700
  40. 40.Best estimate of 79 × 57? (a) 4800 (b) 48000 (c) 480

Answer key

  1. 600
  2. 800
  3. 2800
  4. 700
  5. 700
  6. 800
  7. 600
  8. 2500
  9. 1200
  10. 1000
  11. 1000
  12. 2000
  13. 1000
  14. 5600
  15. 3600
  16. 700
  17. 6000
  18. 1100
  19. 1800
  20. 1000
  21. 1800
  22. 1100
  23. 1600
  24. 900
  25. 400
  26. 1000
  27. 1000
  28. 3600
  29. 800
  30. 600
  31. 1300
  32. 2400
  33. 3200
  34. 800
  35. 2000
  36. 1600
  37. 900
  38. 500
  39. 700
  40. 4800

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