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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 501 · 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 499 + 869? (a) 1600 (b) 1200 (c) 1400
  2. 2.Best estimate of 287 + 518? (a) 1000 (b) 600 (c) 800
  3. 3.Best estimate of 227 + 497? (a) 500 (b) 900 (c) 700
  4. 4.Best estimate of 56 × 24? (a) 12000 (b) 1200 (c) 120
  5. 5.Best estimate of 88 × 14? (a) 900 (b) 9000 (c) 90
  6. 6.Best estimate of 61 × 67? (a) 42000 (b) 4200 (c) 420
  7. 7.Best estimate of 836 + 286? (a) 1100 (b) 1300 (c) 900
  8. 8.Best estimate of 355 + 517? (a) 1100 (b) 900 (c) 700
  9. 9.Best estimate of 507 + 133? (a) 600 (b) 800 (c) 400
  10. 10.Best estimate of 18 × 18? (a) 400 (b) 4000 (c) 40
  11. 11.Best estimate of 610 + 156? (a) 800 (b) 1000 (c) 600
  12. 12.Best estimate of 169 + 458? (a) 500 (b) 700 (c) 900
  13. 13.Best estimate of 851 + 268? (a) 1400 (b) 1200 (c) 1000
  14. 14.Best estimate of 84 × 92? (a) 7200 (b) 72000 (c) 720
  15. 15.Best estimate of 54 × 82? (a) 400 (b) 4000 (c) 40000
  16. 16.Best estimate of 53 × 42? (a) 2000 (b) 20000 (c) 200
  17. 17.Best estimate of 305 + 697? (a) 1200 (b) 800 (c) 1000
  18. 18.Best estimate of 94 × 98? (a) 9000 (b) 90000 (c) 900
  19. 19.Best estimate of 296 + 803? (a) 1300 (b) 900 (c) 1100
  20. 20.Best estimate of 662 + 260? (a) 800 (b) 1200 (c) 1000
  21. 21.Best estimate of 48 × 66? (a) 35000 (b) 3500 (c) 350
  22. 22.Best estimate of 301 + 141? (a) 400 (b) 600 (c) 200
  23. 23.Best estimate of 87 × 38? (a) 3600 (b) 36000 (c) 360
  24. 24.Best estimate of 98 × 76? (a) 80000 (b) 800 (c) 8000
  25. 25.Best estimate of 97 × 31? (a) 30000 (b) 300 (c) 3000
  26. 26.Best estimate of 42 × 98? (a) 40000 (b) 4000 (c) 400
  27. 27.Best estimate of 255 + 465? (a) 800 (b) 600 (c) 1000
  28. 28.Best estimate of 655 + 189? (a) 700 (b) 1100 (c) 900
  29. 29.Best estimate of 807 + 590? (a) 1600 (b) 1400 (c) 1200
  30. 30.Best estimate of 68 × 91? (a) 63000 (b) 6300 (c) 630
  31. 31.Best estimate of 77 × 88? (a) 720 (b) 7200 (c) 72000
  32. 32.Best estimate of 310 + 154? (a) 500 (b) 700 (c) 300
  33. 33.Best estimate of 381 + 637? (a) 800 (b) 1000 (c) 1200
  34. 34.Best estimate of 16 × 41? (a) 8000 (b) 80 (c) 800
  35. 35.Best estimate of 538 + 338? (a) 600 (b) 1000 (c) 800
  36. 36.Best estimate of 83 × 98? (a) 80000 (b) 800 (c) 8000
  37. 37.Best estimate of 64 × 28? (a) 1800 (b) 18000 (c) 180
  38. 38.Best estimate of 346 + 666? (a) 1000 (b) 1200 (c) 800
  39. 39.Best estimate of 572 + 765? (a) 1600 (b) 1400 (c) 1200
  40. 40.Best estimate of 37 × 36? (a) 16000 (b) 1600 (c) 160

Answer key

  1. 1400
  2. 800
  3. 700
  4. 1200
  5. 900
  6. 4200
  7. 1100
  8. 900
  9. 600
  10. 400
  11. 800
  12. 700
  13. 1200
  14. 7200
  15. 4000
  16. 2000
  17. 1000
  18. 9000
  19. 1100
  20. 1000
  21. 3500
  22. 400
  23. 3600
  24. 8000
  25. 3000
  26. 4000
  27. 800
  28. 900
  29. 1400
  30. 6300
  31. 7200
  32. 500
  33. 1000
  34. 800
  35. 800
  36. 8000
  37. 1800
  38. 1000
  39. 1400
  40. 1600

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