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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 301 · 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 22 × 53? (a) 10000 (b) 1000 (c) 100
  2. 2.Best estimate of 46 × 23? (a) 10000 (b) 100 (c) 1000
  3. 3.Best estimate of 497 + 413? (a) 700 (b) 1100 (c) 900
  4. 4.Best estimate of 33 × 64? (a) 1800 (b) 180 (c) 18000
  5. 5.Best estimate of 355 + 363? (a) 600 (b) 800 (c) 1000
  6. 6.Best estimate of 410 + 800? (a) 1400 (b) 1200 (c) 1000
  7. 7.Best estimate of 425 + 652? (a) 900 (b) 1300 (c) 1100
  8. 8.Best estimate of 92 × 81? (a) 720 (b) 7200 (c) 72000
  9. 9.Best estimate of 34 × 29? (a) 900 (b) 90 (c) 9000
  10. 10.Best estimate of 27 × 66? (a) 210 (b) 2100 (c) 21000
  11. 11.Best estimate of 160 + 143? (a) 300 (b) 100 (c) 500
  12. 12.Best estimate of 707 + 219? (a) 700 (b) 1100 (c) 900
  13. 13.Best estimate of 52 × 80? (a) 40000 (b) 4000 (c) 400
  14. 14.Best estimate of 27 × 24? (a) 600 (b) 6000 (c) 60
  15. 15.Best estimate of 39 × 94? (a) 36000 (b) 360 (c) 3600
  16. 16.Best estimate of 87 × 80? (a) 72000 (b) 720 (c) 7200
  17. 17.Best estimate of 251 + 764? (a) 1100 (b) 1300 (c) 900
  18. 18.Best estimate of 96 × 80? (a) 8000 (b) 800 (c) 80000
  19. 19.Best estimate of 74 × 79? (a) 560 (b) 5600 (c) 56000
  20. 20.Best estimate of 401 + 399? (a) 1000 (b) 800 (c) 600
  21. 21.Best estimate of 538 + 342? (a) 1000 (b) 800 (c) 600
  22. 22.Best estimate of 18 × 21? (a) 4000 (b) 40 (c) 400
  23. 23.Best estimate of 860 + 385? (a) 1300 (b) 1500 (c) 1100
  24. 24.Best estimate of 36 × 59? (a) 2400 (b) 24000 (c) 240
  25. 25.Best estimate of 236 + 549? (a) 900 (b) 500 (c) 700
  26. 26.Best estimate of 26 × 57? (a) 1800 (b) 18000 (c) 180
  27. 27.Best estimate of 420 + 779? (a) 1200 (b) 1400 (c) 1000
  28. 28.Best estimate of 362 + 784? (a) 1000 (b) 1200 (c) 1400
  29. 29.Best estimate of 751 + 340? (a) 1100 (b) 1300 (c) 900
  30. 30.Best estimate of 72 × 14? (a) 700 (b) 70 (c) 7000
  31. 31.Best estimate of 777 + 205? (a) 1200 (b) 1000 (c) 800
  32. 32.Best estimate of 31 × 44? (a) 12000 (b) 120 (c) 1200
  33. 33.Best estimate of 60 × 27? (a) 18000 (b) 1800 (c) 180
  34. 34.Best estimate of 66 × 80? (a) 560 (b) 56000 (c) 5600
  35. 35.Best estimate of 397 + 703? (a) 900 (b) 1300 (c) 1100
  36. 36.Best estimate of 78 × 98? (a) 8000 (b) 80000 (c) 800
  37. 37.Best estimate of 575 + 876? (a) 1700 (b) 1300 (c) 1500
  38. 38.Best estimate of 605 + 845? (a) 1200 (b) 1600 (c) 1400
  39. 39.Best estimate of 375 + 692? (a) 1300 (b) 1100 (c) 900
  40. 40.Best estimate of 866 + 613? (a) 1500 (b) 1300 (c) 1700

Answer key

  1. 1000
  2. 1000
  3. 900
  4. 1800
  5. 800
  6. 1200
  7. 1100
  8. 7200
  9. 900
  10. 2100
  11. 300
  12. 900
  13. 4000
  14. 600
  15. 3600
  16. 7200
  17. 1100
  18. 8000
  19. 5600
  20. 800
  21. 800
  22. 400
  23. 1300
  24. 2400
  25. 700
  26. 1800
  27. 1200
  28. 1200
  29. 1100
  30. 700
  31. 1000
  32. 1200
  33. 1800
  34. 5600
  35. 1100
  36. 8000
  37. 1500
  38. 1400
  39. 1100
  40. 1500

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