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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 852 · 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 86 × 48? (a) 4500 (b) 45000 (c) 450
  2. 2.Best estimate of 785 + 455? (a) 1300 (b) 1100 (c) 1500
  3. 3.Best estimate of 30 × 19? (a) 6000 (b) 600 (c) 60
  4. 4.Best estimate of 518 + 351? (a) 700 (b) 1100 (c) 900
  5. 5.Best estimate of 86 × 66? (a) 630 (b) 6300 (c) 63000
  6. 6.Best estimate of 722 + 451? (a) 1400 (b) 1000 (c) 1200
  7. 7.Best estimate of 46 × 74? (a) 3500 (b) 350 (c) 35000
  8. 8.Best estimate of 477 + 474? (a) 800 (b) 1000 (c) 1200
  9. 9.Best estimate of 89 × 29? (a) 27000 (b) 2700 (c) 270
  10. 10.Best estimate of 319 + 749? (a) 1200 (b) 1000 (c) 800
  11. 11.Best estimate of 79 × 71? (a) 5600 (b) 560 (c) 56000
  12. 12.Best estimate of 46 × 46? (a) 25000 (b) 2500 (c) 250
  13. 13.Best estimate of 649 + 171? (a) 1000 (b) 600 (c) 800
  14. 14.Best estimate of 514 + 225? (a) 700 (b) 500 (c) 900
  15. 15.Best estimate of 280 + 675? (a) 1000 (b) 800 (c) 1200
  16. 16.Best estimate of 70 × 52? (a) 3500 (b) 35000 (c) 350
  17. 17.Best estimate of 39 × 96? (a) 40000 (b) 400 (c) 4000
  18. 18.Best estimate of 154 + 342? (a) 500 (b) 300 (c) 700
  19. 19.Best estimate of 68 × 56? (a) 4200 (b) 42000 (c) 420
  20. 20.Best estimate of 575 + 462? (a) 1100 (b) 900 (c) 1300
  21. 21.Best estimate of 66 × 33? (a) 21000 (b) 210 (c) 2100
  22. 22.Best estimate of 69 × 86? (a) 6300 (b) 63000 (c) 630
  23. 23.Best estimate of 815 + 513? (a) 1500 (b) 1100 (c) 1300
  24. 24.Best estimate of 820 + 207? (a) 800 (b) 1200 (c) 1000
  25. 25.Best estimate of 576 + 871? (a) 1300 (b) 1500 (c) 1700
  26. 26.Best estimate of 40 × 20? (a) 800 (b) 80 (c) 8000
  27. 27.Best estimate of 312 + 359? (a) 900 (b) 700 (c) 500
  28. 28.Best estimate of 148 + 539? (a) 400 (b) 600 (c) 800
  29. 29.Best estimate of 46 × 56? (a) 300 (b) 30000 (c) 3000
  30. 30.Best estimate of 96 × 62? (a) 600 (b) 6000 (c) 60000
  31. 31.Best estimate of 586 + 722? (a) 1100 (b) 1500 (c) 1300
  32. 32.Best estimate of 52 × 52? (a) 2500 (b) 25000 (c) 250
  33. 33.Best estimate of 44 × 23? (a) 8000 (b) 800 (c) 80
  34. 34.Best estimate of 20 × 12? (a) 200 (b) 2000 (c) 20
  35. 35.Best estimate of 40 × 67? (a) 280 (b) 28000 (c) 2800
  36. 36.Best estimate of 78 × 46? (a) 40000 (b) 400 (c) 4000
  37. 37.Best estimate of 69 × 30? (a) 21000 (b) 2100 (c) 210
  38. 38.Best estimate of 68 × 24? (a) 1400 (b) 14000 (c) 140
  39. 39.Best estimate of 34 × 69? (a) 2100 (b) 21000 (c) 210
  40. 40.Best estimate of 22 × 48? (a) 1000 (b) 10000 (c) 100

Answer key

  1. 4500
  2. 1300
  3. 600
  4. 900
  5. 6300
  6. 1200
  7. 3500
  8. 1000
  9. 2700
  10. 1000
  11. 5600
  12. 2500
  13. 800
  14. 700
  15. 1000
  16. 3500
  17. 4000
  18. 500
  19. 4200
  20. 1100
  21. 2100
  22. 6300
  23. 1300
  24. 1000
  25. 1500
  26. 800
  27. 700
  28. 600
  29. 3000
  30. 6000
  31. 1300
  32. 2500
  33. 800
  34. 200
  35. 2800
  36. 4000
  37. 2100
  38. 1400
  39. 2100
  40. 1000

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