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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 164 · 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 639 + 343? (a) 1100 (b) 900 (c) 700
  2. 2.Best estimate of 86 × 36? (a) 360 (b) 36000 (c) 3600
  3. 3.Best estimate of 13 × 92? (a) 900 (b) 90 (c) 9000
  4. 4.Best estimate of 49 × 76? (a) 40000 (b) 4000 (c) 400
  5. 5.Best estimate of 658 + 518? (a) 1400 (b) 1200 (c) 1000
  6. 6.Best estimate of 49 × 89? (a) 45000 (b) 450 (c) 4500
  7. 7.Best estimate of 91 × 12? (a) 9000 (b) 900 (c) 90
  8. 8.Best estimate of 832 + 654? (a) 1700 (b) 1300 (c) 1500
  9. 9.Best estimate of 405 + 183? (a) 800 (b) 600 (c) 400
  10. 10.Best estimate of 36 × 40? (a) 16000 (b) 1600 (c) 160
  11. 11.Best estimate of 309 + 807? (a) 1300 (b) 1100 (c) 900
  12. 12.Best estimate of 28 × 40? (a) 1200 (b) 12000 (c) 120
  13. 13.Best estimate of 61 × 19? (a) 1200 (b) 120 (c) 12000
  14. 14.Best estimate of 59 × 16? (a) 120 (b) 1200 (c) 12000
  15. 15.Best estimate of 63 × 36? (a) 2400 (b) 24000 (c) 240
  16. 16.Best estimate of 57 × 73? (a) 42000 (b) 420 (c) 4200
  17. 17.Best estimate of 836 + 762? (a) 1800 (b) 1600 (c) 1400
  18. 18.Best estimate of 92 × 22? (a) 1800 (b) 18000 (c) 180
  19. 19.Best estimate of 663 + 770? (a) 1500 (b) 1700 (c) 1300
  20. 20.Best estimate of 631 + 806? (a) 1400 (b) 1600 (c) 1200
  21. 21.Best estimate of 83 × 87? (a) 7200 (b) 72000 (c) 720
  22. 22.Best estimate of 367 + 875? (a) 1500 (b) 1100 (c) 1300
  23. 23.Best estimate of 714 + 654? (a) 1600 (b) 1200 (c) 1400
  24. 24.Best estimate of 80 × 50? (a) 40000 (b) 400 (c) 4000
  25. 25.Best estimate of 97 × 81? (a) 8000 (b) 80000 (c) 800
  26. 26.Best estimate of 89 × 94? (a) 810 (b) 81000 (c) 8100
  27. 27.Best estimate of 87 × 63? (a) 5400 (b) 540 (c) 54000
  28. 28.Best estimate of 839 + 725? (a) 1500 (b) 1300 (c) 1700
  29. 29.Best estimate of 29 × 33? (a) 9000 (b) 900 (c) 90
  30. 30.Best estimate of 812 + 821? (a) 1400 (b) 1600 (c) 1800
  31. 31.Best estimate of 148 + 530? (a) 600 (b) 800 (c) 400
  32. 32.Best estimate of 386 + 354? (a) 800 (b) 1000 (c) 600
  33. 33.Best estimate of 57 × 29? (a) 180 (b) 18000 (c) 1800
  34. 34.Best estimate of 68 × 19? (a) 1400 (b) 140 (c) 14000
  35. 35.Best estimate of 654 + 290? (a) 1200 (b) 800 (c) 1000
  36. 36.Best estimate of 33 × 56? (a) 180 (b) 18000 (c) 1800
  37. 37.Best estimate of 64 × 52? (a) 30000 (b) 3000 (c) 300
  38. 38.Best estimate of 49 × 20? (a) 10000 (b) 100 (c) 1000
  39. 39.Best estimate of 39 × 14? (a) 400 (b) 4000 (c) 40
  40. 40.Best estimate of 12 × 27? (a) 3000 (b) 300 (c) 30

Answer key

  1. 900
  2. 3600
  3. 900
  4. 4000
  5. 1200
  6. 4500
  7. 900
  8. 1500
  9. 600
  10. 1600
  11. 1100
  12. 1200
  13. 1200
  14. 1200
  15. 2400
  16. 4200
  17. 1600
  18. 1800
  19. 1500
  20. 1400
  21. 7200
  22. 1300
  23. 1400
  24. 4000
  25. 8000
  26. 8100
  27. 5400
  28. 1500
  29. 900
  30. 1600
  31. 600
  32. 800
  33. 1800
  34. 1400
  35. 1000
  36. 1800
  37. 3000
  38. 1000
  39. 400
  40. 300

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