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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 450 · 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 436 + 672? (a) 1300 (b) 900 (c) 1100
  2. 2.Best estimate of 63 × 36? (a) 24000 (b) 2400 (c) 240
  3. 3.Best estimate of 53 × 13? (a) 500 (b) 5000 (c) 50
  4. 4.Best estimate of 81 × 62? (a) 480 (b) 48000 (c) 4800
  5. 5.Best estimate of 247 + 871? (a) 1100 (b) 900 (c) 1300
  6. 6.Best estimate of 31 × 88? (a) 27000 (b) 2700 (c) 270
  7. 7.Best estimate of 14 × 81? (a) 800 (b) 8000 (c) 80
  8. 8.Best estimate of 31 × 29? (a) 900 (b) 9000 (c) 90
  9. 9.Best estimate of 21 × 93? (a) 1800 (b) 180 (c) 18000
  10. 10.Best estimate of 647 + 133? (a) 700 (b) 900 (c) 500
  11. 11.Best estimate of 26 × 66? (a) 2100 (b) 210 (c) 21000
  12. 12.Best estimate of 308 + 292? (a) 600 (b) 400 (c) 800
  13. 13.Best estimate of 67 × 78? (a) 560 (b) 5600 (c) 56000
  14. 14.Best estimate of 71 × 80? (a) 56000 (b) 5600 (c) 560
  15. 15.Best estimate of 26 × 97? (a) 300 (b) 30000 (c) 3000
  16. 16.Best estimate of 292 + 234? (a) 500 (b) 700 (c) 300
  17. 17.Best estimate of 76 × 97? (a) 8000 (b) 800 (c) 80000
  18. 18.Best estimate of 26 × 22? (a) 6000 (b) 600 (c) 60
  19. 19.Best estimate of 747 + 700? (a) 1200 (b) 1400 (c) 1600
  20. 20.Best estimate of 129 + 566? (a) 700 (b) 500 (c) 900
  21. 21.Best estimate of 98 × 21? (a) 20000 (b) 2000 (c) 200
  22. 22.Best estimate of 260 + 545? (a) 1000 (b) 600 (c) 800
  23. 23.Best estimate of 56 × 47? (a) 3000 (b) 30000 (c) 300
  24. 24.Best estimate of 12 × 92? (a) 900 (b) 9000 (c) 90
  25. 25.Best estimate of 50 × 13? (a) 5000 (b) 50 (c) 500
  26. 26.Best estimate of 90 × 51? (a) 45000 (b) 4500 (c) 450
  27. 27.Best estimate of 80 × 78? (a) 6400 (b) 64000 (c) 640
  28. 28.Best estimate of 76 × 67? (a) 56000 (b) 560 (c) 5600
  29. 29.Best estimate of 423 + 546? (a) 1100 (b) 700 (c) 900
  30. 30.Best estimate of 53 × 16? (a) 10000 (b) 100 (c) 1000
  31. 31.Best estimate of 49 × 56? (a) 300 (b) 30000 (c) 3000
  32. 32.Best estimate of 24 × 54? (a) 100 (b) 1000 (c) 10000
  33. 33.Best estimate of 795 + 879? (a) 1500 (b) 1900 (c) 1700
  34. 34.Best estimate of 84 × 49? (a) 4000 (b) 40000 (c) 400
  35. 35.Best estimate of 26 × 36? (a) 1200 (b) 120 (c) 12000
  36. 36.Best estimate of 14 × 47? (a) 50 (b) 5000 (c) 500
  37. 37.Best estimate of 91 × 97? (a) 90000 (b) 9000 (c) 900
  38. 38.Best estimate of 505 + 414? (a) 1100 (b) 900 (c) 700
  39. 39.Best estimate of 251 + 197? (a) 500 (b) 700 (c) 300
  40. 40.Best estimate of 22 × 51? (a) 1000 (b) 10000 (c) 100

Answer key

  1. 1100
  2. 2400
  3. 500
  4. 4800
  5. 1100
  6. 2700
  7. 800
  8. 900
  9. 1800
  10. 700
  11. 2100
  12. 600
  13. 5600
  14. 5600
  15. 3000
  16. 500
  17. 8000
  18. 600
  19. 1400
  20. 700
  21. 2000
  22. 800
  23. 3000
  24. 900
  25. 500
  26. 4500
  27. 6400
  28. 5600
  29. 900
  30. 1000
  31. 3000
  32. 1000
  33. 1700
  34. 4000
  35. 1200
  36. 500
  37. 9000
  38. 900
  39. 500
  40. 1000

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