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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 837 · 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 72 × 36? (a) 28000 (b) 2800 (c) 280
  2. 2.Best estimate of 54 × 72? (a) 3500 (b) 350 (c) 35000
  3. 3.Best estimate of 849 + 449? (a) 1200 (b) 1400 (c) 1000
  4. 4.Best estimate of 26 × 49? (a) 15000 (b) 1500 (c) 150
  5. 5.Best estimate of 81 × 72? (a) 560 (b) 5600 (c) 56000
  6. 6.Best estimate of 197 + 856? (a) 900 (b) 1100 (c) 1300
  7. 7.Best estimate of 84 × 56? (a) 48000 (b) 4800 (c) 480
  8. 8.Best estimate of 424 + 458? (a) 1100 (b) 700 (c) 900
  9. 9.Best estimate of 42 × 64? (a) 24000 (b) 240 (c) 2400
  10. 10.Best estimate of 89 × 71? (a) 6300 (b) 630 (c) 63000
  11. 11.Best estimate of 23 × 57? (a) 1200 (b) 12000 (c) 120
  12. 12.Best estimate of 97 × 26? (a) 3000 (b) 300 (c) 30000
  13. 13.Best estimate of 199 + 740? (a) 900 (b) 1100 (c) 700
  14. 14.Best estimate of 227 + 773? (a) 1200 (b) 1000 (c) 800
  15. 15.Best estimate of 56 × 96? (a) 600 (b) 60000 (c) 6000
  16. 16.Best estimate of 338 + 631? (a) 900 (b) 1100 (c) 700
  17. 17.Best estimate of 711 + 273? (a) 800 (b) 1000 (c) 1200
  18. 18.Best estimate of 81 × 48? (a) 40000 (b) 4000 (c) 400
  19. 19.Best estimate of 709 + 373? (a) 1100 (b) 1300 (c) 900
  20. 20.Best estimate of 337 + 548? (a) 1000 (b) 600 (c) 800
  21. 21.Best estimate of 59 × 92? (a) 5400 (b) 540 (c) 54000
  22. 22.Best estimate of 144 + 391? (a) 500 (b) 300 (c) 700
  23. 23.Best estimate of 39 × 96? (a) 400 (b) 4000 (c) 40000
  24. 24.Best estimate of 124 + 787? (a) 1100 (b) 700 (c) 900
  25. 25.Best estimate of 64 × 70? (a) 42000 (b) 4200 (c) 420
  26. 26.Best estimate of 63 × 47? (a) 300 (b) 30000 (c) 3000
  27. 27.Best estimate of 53 × 59? (a) 300 (b) 3000 (c) 30000
  28. 28.Best estimate of 42 × 23? (a) 800 (b) 8000 (c) 80
  29. 29.Best estimate of 64 × 26? (a) 1800 (b) 18000 (c) 180
  30. 30.Best estimate of 40 × 30? (a) 120 (b) 1200 (c) 12000
  31. 31.Best estimate of 216 + 491? (a) 900 (b) 500 (c) 700
  32. 32.Best estimate of 546 + 168? (a) 700 (b) 900 (c) 500
  33. 33.Best estimate of 229 + 784? (a) 1200 (b) 1000 (c) 800
  34. 34.Best estimate of 22 × 31? (a) 60 (b) 600 (c) 6000
  35. 35.Best estimate of 88 × 57? (a) 540 (b) 54000 (c) 5400
  36. 36.Best estimate of 647 + 777? (a) 1400 (b) 1600 (c) 1200
  37. 37.Best estimate of 28 × 30? (a) 90 (b) 900 (c) 9000
  38. 38.Best estimate of 594 + 771? (a) 1200 (b) 1600 (c) 1400
  39. 39.Best estimate of 477 + 492? (a) 800 (b) 1000 (c) 1200
  40. 40.Best estimate of 633 + 416? (a) 1000 (b) 1200 (c) 800

Answer key

  1. 2800
  2. 3500
  3. 1200
  4. 1500
  5. 5600
  6. 1100
  7. 4800
  8. 900
  9. 2400
  10. 6300
  11. 1200
  12. 3000
  13. 900
  14. 1000
  15. 6000
  16. 900
  17. 1000
  18. 4000
  19. 1100
  20. 800
  21. 5400
  22. 500
  23. 4000
  24. 900
  25. 4200
  26. 3000
  27. 3000
  28. 800
  29. 1800
  30. 1200
  31. 700
  32. 700
  33. 1000
  34. 600
  35. 5400
  36. 1400
  37. 900
  38. 1400
  39. 1000
  40. 1000

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