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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 574 · 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 151 + 168? (a) 600 (b) 200 (c) 400
  2. 2.Best estimate of 551 + 756? (a) 1600 (b) 1400 (c) 1200
  3. 3.Best estimate of 96 × 68? (a) 700 (b) 70000 (c) 7000
  4. 4.Best estimate of 86 × 19? (a) 1800 (b) 18000 (c) 180
  5. 5.Best estimate of 830 + 370? (a) 1000 (b) 1200 (c) 1400
  6. 6.Best estimate of 47 × 34? (a) 1500 (b) 15000 (c) 150
  7. 7.Best estimate of 276 + 593? (a) 700 (b) 900 (c) 1100
  8. 8.Best estimate of 40 × 89? (a) 3600 (b) 360 (c) 36000
  9. 9.Best estimate of 28 × 92? (a) 2700 (b) 270 (c) 27000
  10. 10.Best estimate of 175 + 237? (a) 200 (b) 600 (c) 400
  11. 11.Best estimate of 50 × 52? (a) 25000 (b) 2500 (c) 250
  12. 12.Best estimate of 58 × 33? (a) 180 (b) 1800 (c) 18000
  13. 13.Best estimate of 63 × 37? (a) 2400 (b) 24000 (c) 240
  14. 14.Best estimate of 57 × 40? (a) 24000 (b) 240 (c) 2400
  15. 15.Best estimate of 252 + 229? (a) 500 (b) 300 (c) 700
  16. 16.Best estimate of 432 + 428? (a) 1000 (b) 800 (c) 600
  17. 17.Best estimate of 59 × 72? (a) 42000 (b) 4200 (c) 420
  18. 18.Best estimate of 34 × 86? (a) 2700 (b) 27000 (c) 270
  19. 19.Best estimate of 19 × 52? (a) 10000 (b) 1000 (c) 100
  20. 20.Best estimate of 18 × 62? (a) 1200 (b) 120 (c) 12000
  21. 21.Best estimate of 427 + 155? (a) 400 (b) 600 (c) 800
  22. 22.Best estimate of 97 × 70? (a) 70000 (b) 700 (c) 7000
  23. 23.Best estimate of 32 × 66? (a) 2100 (b) 21000 (c) 210
  24. 24.Best estimate of 84 × 88? (a) 72000 (b) 720 (c) 7200
  25. 25.Best estimate of 43 × 18? (a) 800 (b) 80 (c) 8000
  26. 26.Best estimate of 12 × 72? (a) 700 (b) 7000 (c) 70
  27. 27.Best estimate of 675 + 491? (a) 1000 (b) 1400 (c) 1200
  28. 28.Best estimate of 725 + 404? (a) 1300 (b) 1100 (c) 900
  29. 29.Best estimate of 68 × 42? (a) 28000 (b) 280 (c) 2800
  30. 30.Best estimate of 656 + 526? (a) 1400 (b) 1200 (c) 1000
  31. 31.Best estimate of 512 + 462? (a) 1200 (b) 800 (c) 1000
  32. 32.Best estimate of 830 + 738? (a) 1300 (b) 1500 (c) 1700
  33. 33.Best estimate of 80 × 21? (a) 16000 (b) 1600 (c) 160
  34. 34.Best estimate of 645 + 542? (a) 1300 (b) 1100 (c) 900
  35. 35.Best estimate of 122 + 349? (a) 200 (b) 400 (c) 600
  36. 36.Best estimate of 42 × 43? (a) 160 (b) 1600 (c) 16000
  37. 37.Best estimate of 73 × 86? (a) 630 (b) 63000 (c) 6300
  38. 38.Best estimate of 786 + 599? (a) 1200 (b) 1600 (c) 1400
  39. 39.Best estimate of 821 + 721? (a) 1300 (b) 1700 (c) 1500
  40. 40.Best estimate of 50 × 20? (a) 1000 (b) 10000 (c) 100

Answer key

  1. 400
  2. 1400
  3. 7000
  4. 1800
  5. 1200
  6. 1500
  7. 900
  8. 3600
  9. 2700
  10. 400
  11. 2500
  12. 1800
  13. 2400
  14. 2400
  15. 500
  16. 800
  17. 4200
  18. 2700
  19. 1000
  20. 1200
  21. 600
  22. 7000
  23. 2100
  24. 7200
  25. 800
  26. 700
  27. 1200
  28. 1100
  29. 2800
  30. 1200
  31. 1000
  32. 1500
  33. 1600
  34. 1100
  35. 400
  36. 1600
  37. 6300
  38. 1400
  39. 1500
  40. 1000

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