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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 46 · 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 841 + 191? (a) 1200 (b) 800 (c) 1000
  2. 2.Best estimate of 70 × 12? (a) 700 (b) 70 (c) 7000
  3. 3.Best estimate of 719 + 316? (a) 1200 (b) 1000 (c) 800
  4. 4.Best estimate of 24 × 76? (a) 16000 (b) 160 (c) 1600
  5. 5.Best estimate of 643 + 379? (a) 1200 (b) 800 (c) 1000
  6. 6.Best estimate of 81 × 58? (a) 480 (b) 48000 (c) 4800
  7. 7.Best estimate of 14 × 49? (a) 50 (b) 500 (c) 5000
  8. 8.Best estimate of 78 × 56? (a) 4800 (b) 48000 (c) 480
  9. 9.Best estimate of 797 + 531? (a) 1500 (b) 1100 (c) 1300
  10. 10.Best estimate of 57 × 56? (a) 3600 (b) 36000 (c) 360
  11. 11.Best estimate of 147 + 372? (a) 700 (b) 500 (c) 300
  12. 12.Best estimate of 86 × 52? (a) 4500 (b) 45000 (c) 450
  13. 13.Best estimate of 67 × 81? (a) 5600 (b) 560 (c) 56000
  14. 14.Best estimate of 96 × 98? (a) 10000 (b) 1000 (c) 100000
  15. 15.Best estimate of 140 + 763? (a) 900 (b) 1100 (c) 700
  16. 16.Best estimate of 716 + 165? (a) 1100 (b) 900 (c) 700
  17. 17.Best estimate of 81 × 83? (a) 64000 (b) 640 (c) 6400
  18. 18.Best estimate of 36 × 26? (a) 1200 (b) 120 (c) 12000
  19. 19.Best estimate of 20 × 31? (a) 6000 (b) 600 (c) 60
  20. 20.Best estimate of 779 + 295? (a) 1100 (b) 1300 (c) 900
  21. 21.Best estimate of 72 × 66? (a) 4900 (b) 49000 (c) 490
  22. 22.Best estimate of 14 × 97? (a) 10000 (b) 1000 (c) 100
  23. 23.Best estimate of 28 × 96? (a) 3000 (b) 300 (c) 30000
  24. 24.Best estimate of 290 + 528? (a) 800 (b) 1000 (c) 600
  25. 25.Best estimate of 67 × 63? (a) 42000 (b) 4200 (c) 420
  26. 26.Best estimate of 44 × 43? (a) 1600 (b) 16000 (c) 160
  27. 27.Best estimate of 39 × 69? (a) 2800 (b) 280 (c) 28000
  28. 28.Best estimate of 605 + 257? (a) 900 (b) 700 (c) 1100
  29. 29.Best estimate of 93 × 57? (a) 540 (b) 54000 (c) 5400
  30. 30.Best estimate of 173 + 816? (a) 1000 (b) 1200 (c) 800
  31. 31.Best estimate of 56 × 30? (a) 1800 (b) 18000 (c) 180
  32. 32.Best estimate of 69 × 46? (a) 35000 (b) 3500 (c) 350
  33. 33.Best estimate of 64 × 73? (a) 420 (b) 4200 (c) 42000
  34. 34.Best estimate of 562 + 553? (a) 1000 (b) 1400 (c) 1200
  35. 35.Best estimate of 68 × 16? (a) 14000 (b) 1400 (c) 140
  36. 36.Best estimate of 83 × 30? (a) 2400 (b) 24000 (c) 240
  37. 37.Best estimate of 466 + 642? (a) 1100 (b) 900 (c) 1300
  38. 38.Best estimate of 30 × 37? (a) 12000 (b) 1200 (c) 120
  39. 39.Best estimate of 400 + 528? (a) 700 (b) 1100 (c) 900
  40. 40.Best estimate of 218 + 477? (a) 500 (b) 900 (c) 700

Answer key

  1. 1000
  2. 700
  3. 1000
  4. 1600
  5. 1000
  6. 4800
  7. 500
  8. 4800
  9. 1300
  10. 3600
  11. 500
  12. 4500
  13. 5600
  14. 10000
  15. 900
  16. 900
  17. 6400
  18. 1200
  19. 600
  20. 1100
  21. 4900
  22. 1000
  23. 3000
  24. 800
  25. 4200
  26. 1600
  27. 2800
  28. 900
  29. 5400
  30. 1000
  31. 1800
  32. 3500
  33. 4200
  34. 1200
  35. 1400
  36. 2400
  37. 1100
  38. 1200
  39. 900
  40. 700

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