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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 686 · 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 698 + 851? (a) 1400 (b) 1800 (c) 1600
  2. 2.Best estimate of 26 × 46? (a) 150 (b) 1500 (c) 15000
  3. 3.Best estimate of 79 × 93? (a) 72000 (b) 7200 (c) 720
  4. 4.Best estimate of 490 + 707? (a) 1400 (b) 1200 (c) 1000
  5. 5.Best estimate of 94 × 76? (a) 7200 (b) 720 (c) 72000
  6. 6.Best estimate of 86 × 13? (a) 900 (b) 9000 (c) 90
  7. 7.Best estimate of 849 + 446? (a) 1400 (b) 1000 (c) 1200
  8. 8.Best estimate of 33 × 52? (a) 15000 (b) 150 (c) 1500
  9. 9.Best estimate of 54 × 54? (a) 2500 (b) 250 (c) 25000
  10. 10.Best estimate of 88 × 66? (a) 6300 (b) 630 (c) 63000
  11. 11.Best estimate of 70 × 64? (a) 42000 (b) 420 (c) 4200
  12. 12.Best estimate of 130 + 672? (a) 1000 (b) 600 (c) 800
  13. 13.Best estimate of 289 + 737? (a) 1000 (b) 1200 (c) 800
  14. 14.Best estimate of 233 + 634? (a) 800 (b) 1000 (c) 600
  15. 15.Best estimate of 66 × 81? (a) 5600 (b) 560 (c) 56000
  16. 16.Best estimate of 31 × 53? (a) 150 (b) 1500 (c) 15000
  17. 17.Best estimate of 53 × 27? (a) 1500 (b) 15000 (c) 150
  18. 18.Best estimate of 80 × 70? (a) 5600 (b) 560 (c) 56000
  19. 19.Best estimate of 20 × 26? (a) 600 (b) 6000 (c) 60
  20. 20.Best estimate of 40 × 19? (a) 800 (b) 8000 (c) 80
  21. 21.Best estimate of 91 × 18? (a) 18000 (b) 1800 (c) 180
  22. 22.Best estimate of 83 × 14? (a) 8000 (b) 80 (c) 800
  23. 23.Best estimate of 83 × 94? (a) 7200 (b) 720 (c) 72000
  24. 24.Best estimate of 23 × 33? (a) 600 (b) 6000 (c) 60
  25. 25.Best estimate of 247 + 355? (a) 800 (b) 600 (c) 400
  26. 26.Best estimate of 880 + 222? (a) 1100 (b) 1300 (c) 900
  27. 27.Best estimate of 46 × 97? (a) 50000 (b) 5000 (c) 500
  28. 28.Best estimate of 532 + 741? (a) 1000 (b) 1200 (c) 1400
  29. 29.Best estimate of 69 × 82? (a) 5600 (b) 56000 (c) 560
  30. 30.Best estimate of 415 + 788? (a) 1400 (b) 1200 (c) 1000
  31. 31.Best estimate of 759 + 303? (a) 900 (b) 1100 (c) 1300
  32. 32.Best estimate of 565 + 546? (a) 1100 (b) 1300 (c) 900
  33. 33.Best estimate of 345 + 707? (a) 800 (b) 1000 (c) 1200
  34. 34.Best estimate of 76 × 80? (a) 640 (b) 64000 (c) 6400
  35. 35.Best estimate of 96 × 86? (a) 900 (b) 90000 (c) 9000
  36. 36.Best estimate of 94 × 20? (a) 18000 (b) 180 (c) 1800
  37. 37.Best estimate of 485 + 181? (a) 700 (b) 900 (c) 500
  38. 38.Best estimate of 831 + 322? (a) 1300 (b) 900 (c) 1100
  39. 39.Best estimate of 42 × 88? (a) 360 (b) 3600 (c) 36000
  40. 40.Best estimate of 622 + 168? (a) 800 (b) 600 (c) 1000

Answer key

  1. 1600
  2. 1500
  3. 7200
  4. 1200
  5. 7200
  6. 900
  7. 1200
  8. 1500
  9. 2500
  10. 6300
  11. 4200
  12. 800
  13. 1000
  14. 800
  15. 5600
  16. 1500
  17. 1500
  18. 5600
  19. 600
  20. 800
  21. 1800
  22. 800
  23. 7200
  24. 600
  25. 600
  26. 1100
  27. 5000
  28. 1200
  29. 5600
  30. 1200
  31. 1100
  32. 1100
  33. 1000
  34. 6400
  35. 9000
  36. 1800
  37. 700
  38. 1100
  39. 3600
  40. 800

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