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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 836 · 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 505 + 226? (a) 900 (b) 700 (c) 500
  2. 2.Best estimate of 82 × 26? (a) 24000 (b) 2400 (c) 240
  3. 3.Best estimate of 89 × 83? (a) 7200 (b) 720 (c) 72000
  4. 4.Best estimate of 76 × 93? (a) 720 (b) 72000 (c) 7200
  5. 5.Best estimate of 19 × 78? (a) 16000 (b) 1600 (c) 160
  6. 6.Best estimate of 387 + 771? (a) 1000 (b) 1400 (c) 1200
  7. 7.Best estimate of 126 + 721? (a) 1000 (b) 600 (c) 800
  8. 8.Best estimate of 46 × 54? (a) 2500 (b) 250 (c) 25000
  9. 9.Best estimate of 607 + 209? (a) 600 (b) 1000 (c) 800
  10. 10.Best estimate of 96 × 98? (a) 10000 (b) 1000 (c) 100000
  11. 11.Best estimate of 444 + 133? (a) 300 (b) 700 (c) 500
  12. 12.Best estimate of 836 + 259? (a) 1100 (b) 1300 (c) 900
  13. 13.Best estimate of 304 + 862? (a) 1200 (b) 1400 (c) 1000
  14. 14.Best estimate of 79 × 42? (a) 3200 (b) 32000 (c) 320
  15. 15.Best estimate of 56 × 36? (a) 2400 (b) 240 (c) 24000
  16. 16.Best estimate of 57 × 97? (a) 6000 (b) 60000 (c) 600
  17. 17.Best estimate of 201 + 619? (a) 1000 (b) 800 (c) 600
  18. 18.Best estimate of 17 × 20? (a) 400 (b) 4000 (c) 40
  19. 19.Best estimate of 595 + 797? (a) 1600 (b) 1200 (c) 1400
  20. 20.Best estimate of 91 × 86? (a) 810 (b) 81000 (c) 8100
  21. 21.Best estimate of 792 + 560? (a) 1600 (b) 1400 (c) 1200
  22. 22.Best estimate of 409 + 522? (a) 700 (b) 1100 (c) 900
  23. 23.Best estimate of 39 × 76? (a) 3200 (b) 320 (c) 32000
  24. 24.Best estimate of 473 + 411? (a) 700 (b) 1100 (c) 900
  25. 25.Best estimate of 71 × 60? (a) 420 (b) 42000 (c) 4200
  26. 26.Best estimate of 704 + 796? (a) 1500 (b) 1300 (c) 1700
  27. 27.Best estimate of 96 × 38? (a) 400 (b) 40000 (c) 4000
  28. 28.Best estimate of 51 × 43? (a) 20000 (b) 200 (c) 2000
  29. 29.Best estimate of 22 × 51? (a) 10000 (b) 1000 (c) 100
  30. 30.Best estimate of 28 × 12? (a) 30 (b) 300 (c) 3000
  31. 31.Best estimate of 121 + 630? (a) 900 (b) 700 (c) 500
  32. 32.Best estimate of 596 + 209? (a) 1000 (b) 800 (c) 600
  33. 33.Best estimate of 297 + 613? (a) 700 (b) 900 (c) 1100
  34. 34.Best estimate of 32 × 78? (a) 2400 (b) 24000 (c) 240
  35. 35.Best estimate of 355 + 267? (a) 500 (b) 900 (c) 700
  36. 36.Best estimate of 22 × 30? (a) 600 (b) 60 (c) 6000
  37. 37.Best estimate of 715 + 654? (a) 1600 (b) 1200 (c) 1400
  38. 38.Best estimate of 40 × 57? (a) 2400 (b) 24000 (c) 240
  39. 39.Best estimate of 19 × 91? (a) 180 (b) 18000 (c) 1800
  40. 40.Best estimate of 46 × 84? (a) 400 (b) 40000 (c) 4000

Answer key

  1. 700
  2. 2400
  3. 7200
  4. 7200
  5. 1600
  6. 1200
  7. 800
  8. 2500
  9. 800
  10. 10000
  11. 500
  12. 1100
  13. 1200
  14. 3200
  15. 2400
  16. 6000
  17. 800
  18. 400
  19. 1400
  20. 8100
  21. 1400
  22. 900
  23. 3200
  24. 900
  25. 4200
  26. 1500
  27. 4000
  28. 2000
  29. 1000
  30. 300
  31. 700
  32. 800
  33. 900
  34. 2400
  35. 700
  36. 600
  37. 1400
  38. 2400
  39. 1800
  40. 4000

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