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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 5 · 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 837 + 177? (a) 800 (b) 1000 (c) 1200
  2. 2.Best estimate of 20 × 28? (a) 600 (b) 6000 (c) 60
  3. 3.Best estimate of 46 × 36? (a) 2000 (b) 20000 (c) 200
  4. 4.Best estimate of 33 × 66? (a) 210 (b) 21000 (c) 2100
  5. 5.Best estimate of 62 × 20? (a) 12000 (b) 1200 (c) 120
  6. 6.Best estimate of 74 × 66? (a) 49000 (b) 490 (c) 4900
  7. 7.Best estimate of 38 × 46? (a) 20000 (b) 2000 (c) 200
  8. 8.Best estimate of 733 + 806? (a) 1300 (b) 1500 (c) 1700
  9. 9.Best estimate of 145 + 596? (a) 700 (b) 500 (c) 900
  10. 10.Best estimate of 73 × 66? (a) 4900 (b) 490 (c) 49000
  11. 11.Best estimate of 80 × 50? (a) 40000 (b) 400 (c) 4000
  12. 12.Best estimate of 47 × 20? (a) 10000 (b) 1000 (c) 100
  13. 13.Best estimate of 27 × 44? (a) 1200 (b) 12000 (c) 120
  14. 14.Best estimate of 709 + 403? (a) 900 (b) 1300 (c) 1100
  15. 15.Best estimate of 403 + 478? (a) 1100 (b) 700 (c) 900
  16. 16.Best estimate of 220 + 586? (a) 800 (b) 1000 (c) 600
  17. 17.Best estimate of 13 × 26? (a) 300 (b) 3000 (c) 30
  18. 18.Best estimate of 751 + 606? (a) 1600 (b) 1200 (c) 1400
  19. 19.Best estimate of 68 × 62? (a) 42000 (b) 4200 (c) 420
  20. 20.Best estimate of 398 + 747? (a) 900 (b) 1100 (c) 1300
  21. 21.Best estimate of 398 + 345? (a) 500 (b) 900 (c) 700
  22. 22.Best estimate of 56 × 40? (a) 24000 (b) 240 (c) 2400
  23. 23.Best estimate of 817 + 174? (a) 1200 (b) 800 (c) 1000
  24. 24.Best estimate of 49 × 60? (a) 30000 (b) 300 (c) 3000
  25. 25.Best estimate of 86 × 64? (a) 5400 (b) 540 (c) 54000
  26. 26.Best estimate of 56 × 91? (a) 54000 (b) 5400 (c) 540
  27. 27.Best estimate of 598 + 425? (a) 800 (b) 1000 (c) 1200
  28. 28.Best estimate of 59 × 88? (a) 5400 (b) 54000 (c) 540
  29. 29.Best estimate of 433 + 542? (a) 700 (b) 900 (c) 1100
  30. 30.Best estimate of 22 × 26? (a) 600 (b) 60 (c) 6000
  31. 31.Best estimate of 22 × 13? (a) 200 (b) 2000 (c) 20
  32. 32.Best estimate of 358 + 487? (a) 1100 (b) 700 (c) 900
  33. 33.Best estimate of 12 × 60? (a) 6000 (b) 600 (c) 60
  34. 34.Best estimate of 86 × 66? (a) 630 (b) 63000 (c) 6300
  35. 35.Best estimate of 699 + 505? (a) 1400 (b) 1000 (c) 1200
  36. 36.Best estimate of 776 + 636? (a) 1400 (b) 1600 (c) 1200
  37. 37.Best estimate of 54 × 42? (a) 20000 (b) 200 (c) 2000
  38. 38.Best estimate of 357 + 745? (a) 1300 (b) 900 (c) 1100
  39. 39.Best estimate of 523 + 359? (a) 700 (b) 1100 (c) 900
  40. 40.Best estimate of 272 + 319? (a) 400 (b) 800 (c) 600

Answer key

  1. 1000
  2. 600
  3. 2000
  4. 2100
  5. 1200
  6. 4900
  7. 2000
  8. 1500
  9. 700
  10. 4900
  11. 4000
  12. 1000
  13. 1200
  14. 1100
  15. 900
  16. 800
  17. 300
  18. 1400
  19. 4200
  20. 1100
  21. 700
  22. 2400
  23. 1000
  24. 3000
  25. 5400
  26. 5400
  27. 1000
  28. 5400
  29. 900
  30. 600
  31. 200
  32. 900
  33. 600
  34. 6300
  35. 1200
  36. 1400
  37. 2000
  38. 1100
  39. 900
  40. 600

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