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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 355 · 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 482 + 465? (a) 1200 (b) 1000 (c) 800
  2. 2.Best estimate of 21 × 69? (a) 1400 (b) 140 (c) 14000
  3. 3.Best estimate of 599 + 284? (a) 1100 (b) 700 (c) 900
  4. 4.Best estimate of 857 + 867? (a) 2000 (b) 1800 (c) 1600
  5. 5.Best estimate of 385 + 289? (a) 500 (b) 700 (c) 900
  6. 6.Best estimate of 575 + 188? (a) 1000 (b) 800 (c) 600
  7. 7.Best estimate of 84 × 51? (a) 40000 (b) 4000 (c) 400
  8. 8.Best estimate of 275 + 361? (a) 500 (b) 900 (c) 700
  9. 9.Best estimate of 68 × 31? (a) 210 (b) 2100 (c) 21000
  10. 10.Best estimate of 71 × 28? (a) 21000 (b) 210 (c) 2100
  11. 11.Best estimate of 229 + 360? (a) 600 (b) 400 (c) 800
  12. 12.Best estimate of 56 × 26? (a) 1800 (b) 18000 (c) 180
  13. 13.Best estimate of 94 × 16? (a) 18000 (b) 180 (c) 1800
  14. 14.Best estimate of 52 × 68? (a) 3500 (b) 350 (c) 35000
  15. 15.Best estimate of 821 + 503? (a) 1300 (b) 1100 (c) 1500
  16. 16.Best estimate of 76 × 94? (a) 7200 (b) 720 (c) 72000
  17. 17.Best estimate of 66 × 57? (a) 42000 (b) 4200 (c) 420
  18. 18.Best estimate of 71 × 77? (a) 56000 (b) 5600 (c) 560
  19. 19.Best estimate of 90 × 49? (a) 45000 (b) 4500 (c) 450
  20. 20.Best estimate of 264 + 519? (a) 800 (b) 1000 (c) 600
  21. 21.Best estimate of 599 + 564? (a) 1400 (b) 1000 (c) 1200
  22. 22.Best estimate of 26 × 36? (a) 12000 (b) 120 (c) 1200
  23. 23.Best estimate of 67 × 23? (a) 140 (b) 14000 (c) 1400
  24. 24.Best estimate of 21 × 21? (a) 40 (b) 400 (c) 4000
  25. 25.Best estimate of 327 + 765? (a) 1100 (b) 900 (c) 1300
  26. 26.Best estimate of 33 × 59? (a) 180 (b) 18000 (c) 1800
  27. 27.Best estimate of 754 + 259? (a) 1300 (b) 1100 (c) 900
  28. 28.Best estimate of 553 + 639? (a) 1000 (b) 1200 (c) 1400
  29. 29.Best estimate of 456 + 491? (a) 1000 (b) 800 (c) 1200
  30. 30.Best estimate of 21 × 36? (a) 8000 (b) 80 (c) 800
  31. 31.Best estimate of 313 + 417? (a) 500 (b) 700 (c) 900
  32. 32.Best estimate of 269 + 405? (a) 900 (b) 700 (c) 500
  33. 33.Best estimate of 20 × 36? (a) 8000 (b) 800 (c) 80
  34. 34.Best estimate of 93 × 46? (a) 45000 (b) 450 (c) 4500
  35. 35.Best estimate of 415 + 749? (a) 1100 (b) 1300 (c) 900
  36. 36.Best estimate of 61 × 74? (a) 420 (b) 42000 (c) 4200
  37. 37.Best estimate of 74 × 16? (a) 14000 (b) 140 (c) 1400
  38. 38.Best estimate of 241 + 141? (a) 500 (b) 300 (c) 100
  39. 39.Best estimate of 31 × 54? (a) 1500 (b) 15000 (c) 150
  40. 40.Best estimate of 366 + 398? (a) 600 (b) 1000 (c) 800

Answer key

  1. 1000
  2. 1400
  3. 900
  4. 1800
  5. 700
  6. 800
  7. 4000
  8. 700
  9. 2100
  10. 2100
  11. 600
  12. 1800
  13. 1800
  14. 3500
  15. 1300
  16. 7200
  17. 4200
  18. 5600
  19. 4500
  20. 800
  21. 1200
  22. 1200
  23. 1400
  24. 400
  25. 1100
  26. 1800
  27. 1100
  28. 1200
  29. 1000
  30. 800
  31. 700
  32. 700
  33. 800
  34. 4500
  35. 1100
  36. 4200
  37. 1400
  38. 300
  39. 1500
  40. 800

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