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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 673 · 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 37 × 60? (a) 24000 (b) 240 (c) 2400
  2. 2.Best estimate of 534 + 815? (a) 1500 (b) 1100 (c) 1300
  3. 3.Best estimate of 50 × 26? (a) 150 (b) 15000 (c) 1500
  4. 4.Best estimate of 762 + 165? (a) 1200 (b) 1000 (c) 800
  5. 5.Best estimate of 33 × 76? (a) 24000 (b) 2400 (c) 240
  6. 6.Best estimate of 12 × 90? (a) 9000 (b) 900 (c) 90
  7. 7.Best estimate of 320 + 510? (a) 1000 (b) 600 (c) 800
  8. 8.Best estimate of 63 × 88? (a) 5400 (b) 54000 (c) 540
  9. 9.Best estimate of 845 + 166? (a) 800 (b) 1200 (c) 1000
  10. 10.Best estimate of 70 × 79? (a) 5600 (b) 56000 (c) 560
  11. 11.Best estimate of 338 + 235? (a) 500 (b) 700 (c) 300
  12. 12.Best estimate of 17 × 36? (a) 80 (b) 8000 (c) 800
  13. 13.Best estimate of 23 × 97? (a) 20000 (b) 2000 (c) 200
  14. 14.Best estimate of 16 × 92? (a) 18000 (b) 1800 (c) 180
  15. 15.Best estimate of 76 × 56? (a) 480 (b) 48000 (c) 4800
  16. 16.Best estimate of 36 × 28? (a) 1200 (b) 120 (c) 12000
  17. 17.Best estimate of 689 + 172? (a) 700 (b) 900 (c) 1100
  18. 18.Best estimate of 92 × 56? (a) 54000 (b) 5400 (c) 540
  19. 19.Best estimate of 638 + 878? (a) 1500 (b) 1300 (c) 1700
  20. 20.Best estimate of 655 + 168? (a) 900 (b) 700 (c) 1100
  21. 21.Best estimate of 190 + 538? (a) 700 (b) 900 (c) 500
  22. 22.Best estimate of 29 × 12? (a) 300 (b) 30 (c) 3000
  23. 23.Best estimate of 28 × 26? (a) 9000 (b) 900 (c) 90
  24. 24.Best estimate of 89 × 18? (a) 1800 (b) 180 (c) 18000
  25. 25.Best estimate of 515 + 873? (a) 1200 (b) 1600 (c) 1400
  26. 26.Best estimate of 670 + 806? (a) 1300 (b) 1700 (c) 1500
  27. 27.Best estimate of 694 + 155? (a) 700 (b) 1100 (c) 900
  28. 28.Best estimate of 477 + 607? (a) 1300 (b) 1100 (c) 900
  29. 29.Best estimate of 152 + 503? (a) 900 (b) 500 (c) 700
  30. 30.Best estimate of 335 + 547? (a) 800 (b) 1000 (c) 600
  31. 31.Best estimate of 858 + 122? (a) 800 (b) 1000 (c) 1200
  32. 32.Best estimate of 29 × 22? (a) 60 (b) 6000 (c) 600
  33. 33.Best estimate of 23 × 84? (a) 160 (b) 16000 (c) 1600
  34. 34.Best estimate of 507 + 657? (a) 1200 (b) 1400 (c) 1000
  35. 35.Best estimate of 275 + 346? (a) 600 (b) 800 (c) 400
  36. 36.Best estimate of 31 × 92? (a) 270 (b) 2700 (c) 27000
  37. 37.Best estimate of 40 × 94? (a) 36000 (b) 3600 (c) 360
  38. 38.Best estimate of 539 + 217? (a) 900 (b) 700 (c) 500
  39. 39.Best estimate of 707 + 704? (a) 1600 (b) 1400 (c) 1200
  40. 40.Best estimate of 56 × 34? (a) 180 (b) 1800 (c) 18000

Answer key

  1. 2400
  2. 1300
  3. 1500
  4. 1000
  5. 2400
  6. 900
  7. 800
  8. 5400
  9. 1000
  10. 5600
  11. 500
  12. 800
  13. 2000
  14. 1800
  15. 4800
  16. 1200
  17. 900
  18. 5400
  19. 1500
  20. 900
  21. 700
  22. 300
  23. 900
  24. 1800
  25. 1400
  26. 1500
  27. 900
  28. 1100
  29. 700
  30. 800
  31. 1000
  32. 600
  33. 1600
  34. 1200
  35. 600
  36. 2700
  37. 3600
  38. 700
  39. 1400
  40. 1800

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