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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 290 · 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 482 + 147? (a) 400 (b) 800 (c) 600
  2. 2.Best estimate of 20 × 22? (a) 4000 (b) 40 (c) 400
  3. 3.Best estimate of 23 × 57? (a) 120 (b) 12000 (c) 1200
  4. 4.Best estimate of 43 × 23? (a) 80 (b) 800 (c) 8000
  5. 5.Best estimate of 41 × 82? (a) 3200 (b) 320 (c) 32000
  6. 6.Best estimate of 34 × 21? (a) 600 (b) 6000 (c) 60
  7. 7.Best estimate of 19 × 49? (a) 100 (b) 1000 (c) 10000
  8. 8.Best estimate of 57 × 62? (a) 3600 (b) 360 (c) 36000
  9. 9.Best estimate of 20 × 96? (a) 200 (b) 20000 (c) 2000
  10. 10.Best estimate of 668 + 613? (a) 1500 (b) 1100 (c) 1300
  11. 11.Best estimate of 403 + 349? (a) 900 (b) 500 (c) 700
  12. 12.Best estimate of 417 + 133? (a) 300 (b) 500 (c) 700
  13. 13.Best estimate of 766 + 705? (a) 1300 (b) 1700 (c) 1500
  14. 14.Best estimate of 33 × 34? (a) 900 (b) 9000 (c) 90
  15. 15.Best estimate of 347 + 221? (a) 300 (b) 500 (c) 700
  16. 16.Best estimate of 493 + 236? (a) 700 (b) 900 (c) 500
  17. 17.Best estimate of 81 × 16? (a) 160 (b) 16000 (c) 1600
  18. 18.Best estimate of 80 × 92? (a) 72000 (b) 7200 (c) 720
  19. 19.Best estimate of 259 + 573? (a) 900 (b) 700 (c) 1100
  20. 20.Best estimate of 34 × 80? (a) 2400 (b) 240 (c) 24000
  21. 21.Best estimate of 29 × 27? (a) 9000 (b) 90 (c) 900
  22. 22.Best estimate of 357 + 818? (a) 1000 (b) 1200 (c) 1400
  23. 23.Best estimate of 97 × 27? (a) 30000 (b) 3000 (c) 300
  24. 24.Best estimate of 16 × 27? (a) 600 (b) 60 (c) 6000
  25. 25.Best estimate of 130 + 231? (a) 100 (b) 300 (c) 500
  26. 26.Best estimate of 590 + 188? (a) 800 (b) 1000 (c) 600
  27. 27.Best estimate of 80 × 33? (a) 2400 (b) 240 (c) 24000
  28. 28.Best estimate of 468 + 187? (a) 900 (b) 500 (c) 700
  29. 29.Best estimate of 20 × 26? (a) 600 (b) 60 (c) 6000
  30. 30.Best estimate of 12 × 80? (a) 80 (b) 800 (c) 8000
  31. 31.Best estimate of 98 × 58? (a) 6000 (b) 60000 (c) 600
  32. 32.Best estimate of 32 × 94? (a) 2700 (b) 27000 (c) 270
  33. 33.Best estimate of 91 × 68? (a) 6300 (b) 630 (c) 63000
  34. 34.Best estimate of 74 × 61? (a) 42000 (b) 420 (c) 4200
  35. 35.Best estimate of 490 + 408? (a) 900 (b) 700 (c) 1100
  36. 36.Best estimate of 315 + 648? (a) 1100 (b) 900 (c) 700
  37. 37.Best estimate of 557 + 319? (a) 900 (b) 700 (c) 1100
  38. 38.Best estimate of 30 × 26? (a) 900 (b) 90 (c) 9000
  39. 39.Best estimate of 204 + 244? (a) 400 (b) 200 (c) 600
  40. 40.Best estimate of 32 × 39? (a) 1200 (b) 12000 (c) 120

Answer key

  1. 600
  2. 400
  3. 1200
  4. 800
  5. 3200
  6. 600
  7. 1000
  8. 3600
  9. 2000
  10. 1300
  11. 700
  12. 500
  13. 1500
  14. 900
  15. 500
  16. 700
  17. 1600
  18. 7200
  19. 900
  20. 2400
  21. 900
  22. 1200
  23. 3000
  24. 600
  25. 300
  26. 800
  27. 2400
  28. 700
  29. 600
  30. 800
  31. 6000
  32. 2700
  33. 6300
  34. 4200
  35. 900
  36. 900
  37. 900
  38. 900
  39. 400
  40. 1200

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