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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 334 · 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 61 × 30? (a) 180 (b) 1800 (c) 18000
  2. 2.Best estimate of 32 × 93? (a) 2700 (b) 27000 (c) 270
  3. 3.Best estimate of 21 × 62? (a) 1200 (b) 120 (c) 12000
  4. 4.Best estimate of 287 + 305? (a) 400 (b) 600 (c) 800
  5. 5.Best estimate of 487 + 839? (a) 1300 (b) 1100 (c) 1500
  6. 6.Best estimate of 50 × 13? (a) 500 (b) 5000 (c) 50
  7. 7.Best estimate of 49 × 86? (a) 45000 (b) 450 (c) 4500
  8. 8.Best estimate of 179 + 649? (a) 1000 (b) 800 (c) 600
  9. 9.Best estimate of 86 × 31? (a) 27000 (b) 2700 (c) 270
  10. 10.Best estimate of 46 × 36? (a) 200 (b) 20000 (c) 2000
  11. 11.Best estimate of 237 + 836? (a) 1200 (b) 800 (c) 1000
  12. 12.Best estimate of 26 × 66? (a) 210 (b) 21000 (c) 2100
  13. 13.Best estimate of 265 + 135? (a) 600 (b) 400 (c) 200
  14. 14.Best estimate of 270 + 861? (a) 1400 (b) 1000 (c) 1200
  15. 15.Best estimate of 38 × 96? (a) 4000 (b) 40000 (c) 400
  16. 16.Best estimate of 815 + 349? (a) 900 (b) 1100 (c) 1300
  17. 17.Best estimate of 96 × 83? (a) 80000 (b) 800 (c) 8000
  18. 18.Best estimate of 53 × 51? (a) 25000 (b) 250 (c) 2500
  19. 19.Best estimate of 240 + 723? (a) 1100 (b) 700 (c) 900
  20. 20.Best estimate of 41 × 86? (a) 3600 (b) 36000 (c) 360
  21. 21.Best estimate of 26 × 20? (a) 6000 (b) 600 (c) 60
  22. 22.Best estimate of 467 + 857? (a) 1200 (b) 1600 (c) 1400
  23. 23.Best estimate of 64 × 46? (a) 300 (b) 3000 (c) 30000
  24. 24.Best estimate of 244 + 738? (a) 900 (b) 700 (c) 1100
  25. 25.Best estimate of 857 + 452? (a) 1600 (b) 1400 (c) 1200
  26. 26.Best estimate of 263 + 861? (a) 1200 (b) 1400 (c) 1000
  27. 27.Best estimate of 793 + 584? (a) 1200 (b) 1400 (c) 1600
  28. 28.Best estimate of 124 + 871? (a) 1000 (b) 800 (c) 1200
  29. 29.Best estimate of 20 × 31? (a) 600 (b) 6000 (c) 60
  30. 30.Best estimate of 38 × 72? (a) 28000 (b) 280 (c) 2800
  31. 31.Best estimate of 425 + 274? (a) 900 (b) 500 (c) 700
  32. 32.Best estimate of 87 × 84? (a) 72000 (b) 7200 (c) 720
  33. 33.Best estimate of 822 + 222? (a) 1200 (b) 800 (c) 1000
  34. 34.Best estimate of 158 + 513? (a) 900 (b) 500 (c) 700
  35. 35.Best estimate of 43 × 24? (a) 8000 (b) 800 (c) 80
  36. 36.Best estimate of 820 + 256? (a) 1300 (b) 1100 (c) 900
  37. 37.Best estimate of 49 × 23? (a) 1000 (b) 10000 (c) 100
  38. 38.Best estimate of 39 × 96? (a) 40000 (b) 400 (c) 4000
  39. 39.Best estimate of 20 × 62? (a) 1200 (b) 12000 (c) 120
  40. 40.Best estimate of 67 × 89? (a) 6300 (b) 630 (c) 63000

Answer key

  1. 1800
  2. 2700
  3. 1200
  4. 600
  5. 1300
  6. 500
  7. 4500
  8. 800
  9. 2700
  10. 2000
  11. 1000
  12. 2100
  13. 400
  14. 1200
  15. 4000
  16. 1100
  17. 8000
  18. 2500
  19. 900
  20. 3600
  21. 600
  22. 1400
  23. 3000
  24. 900
  25. 1400
  26. 1200
  27. 1400
  28. 1000
  29. 600
  30. 2800
  31. 700
  32. 7200
  33. 1000
  34. 700
  35. 800
  36. 1100
  37. 1000
  38. 4000
  39. 1200
  40. 6300

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