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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 706 · 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 173 + 396? (a) 600 (b) 400 (c) 800
  2. 2.Best estimate of 580 + 158? (a) 800 (b) 600 (c) 1000
  3. 3.Best estimate of 156 + 691? (a) 700 (b) 900 (c) 1100
  4. 4.Best estimate of 619 + 875? (a) 1500 (b) 1700 (c) 1300
  5. 5.Best estimate of 49 × 56? (a) 30000 (b) 3000 (c) 300
  6. 6.Best estimate of 46 × 47? (a) 250 (b) 25000 (c) 2500
  7. 7.Best estimate of 21 × 44? (a) 80 (b) 800 (c) 8000
  8. 8.Best estimate of 41 × 19? (a) 80 (b) 800 (c) 8000
  9. 9.Best estimate of 520 + 812? (a) 1500 (b) 1300 (c) 1100
  10. 10.Best estimate of 849 + 748? (a) 1700 (b) 1300 (c) 1500
  11. 11.Best estimate of 339 + 600? (a) 900 (b) 1100 (c) 700
  12. 12.Best estimate of 551 + 165? (a) 1000 (b) 800 (c) 600
  13. 13.Best estimate of 41 × 51? (a) 20000 (b) 200 (c) 2000
  14. 14.Best estimate of 787 + 397? (a) 1400 (b) 1000 (c) 1200
  15. 15.Best estimate of 60 × 20? (a) 12000 (b) 120 (c) 1200
  16. 16.Best estimate of 805 + 559? (a) 1400 (b) 1600 (c) 1200
  17. 17.Best estimate of 248 + 640? (a) 800 (b) 600 (c) 1000
  18. 18.Best estimate of 30 × 72? (a) 2100 (b) 21000 (c) 210
  19. 19.Best estimate of 596 + 854? (a) 1300 (b) 1500 (c) 1700
  20. 20.Best estimate of 639 + 340? (a) 700 (b) 900 (c) 1100
  21. 21.Best estimate of 96 × 37? (a) 400 (b) 4000 (c) 40000
  22. 22.Best estimate of 797 + 209? (a) 1000 (b) 800 (c) 1200
  23. 23.Best estimate of 96 × 53? (a) 500 (b) 50000 (c) 5000
  24. 24.Best estimate of 66 × 92? (a) 63000 (b) 630 (c) 6300
  25. 25.Best estimate of 37 × 63? (a) 24000 (b) 2400 (c) 240
  26. 26.Best estimate of 221 + 346? (a) 500 (b) 300 (c) 700
  27. 27.Best estimate of 683 + 212? (a) 1100 (b) 700 (c) 900
  28. 28.Best estimate of 31 × 53? (a) 15000 (b) 150 (c) 1500
  29. 29.Best estimate of 73 × 42? (a) 2800 (b) 280 (c) 28000
  30. 30.Best estimate of 310 + 813? (a) 900 (b) 1300 (c) 1100
  31. 31.Best estimate of 44 × 31? (a) 1200 (b) 12000 (c) 120
  32. 32.Best estimate of 797 + 748? (a) 1300 (b) 1500 (c) 1700
  33. 33.Best estimate of 294 + 528? (a) 800 (b) 1000 (c) 600
  34. 34.Best estimate of 37 × 49? (a) 2000 (b) 200 (c) 20000
  35. 35.Best estimate of 189 + 225? (a) 600 (b) 400 (c) 200
  36. 36.Best estimate of 776 + 415? (a) 1000 (b) 1400 (c) 1200
  37. 37.Best estimate of 27 × 21? (a) 6000 (b) 60 (c) 600
  38. 38.Best estimate of 56 × 16? (a) 12000 (b) 1200 (c) 120
  39. 39.Best estimate of 18 × 51? (a) 1000 (b) 100 (c) 10000
  40. 40.Best estimate of 36 × 46? (a) 200 (b) 20000 (c) 2000

Answer key

  1. 600
  2. 800
  3. 900
  4. 1500
  5. 3000
  6. 2500
  7. 800
  8. 800
  9. 1300
  10. 1500
  11. 900
  12. 800
  13. 2000
  14. 1200
  15. 1200
  16. 1400
  17. 800
  18. 2100
  19. 1500
  20. 900
  21. 4000
  22. 1000
  23. 5000
  24. 6300
  25. 2400
  26. 500
  27. 900
  28. 1500
  29. 2800
  30. 1100
  31. 1200
  32. 1500
  33. 800
  34. 2000
  35. 400
  36. 1200
  37. 600
  38. 1200
  39. 1000
  40. 2000

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