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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 414 · 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 66 × 16? (a) 140 (b) 14000 (c) 1400
  2. 2.Best estimate of 18 × 79? (a) 160 (b) 16000 (c) 1600
  3. 3.Best estimate of 870 + 345? (a) 1200 (b) 1400 (c) 1000
  4. 4.Best estimate of 233 + 439? (a) 400 (b) 800 (c) 600
  5. 5.Best estimate of 213 + 284? (a) 700 (b) 500 (c) 300
  6. 6.Best estimate of 23 × 72? (a) 1400 (b) 14000 (c) 140
  7. 7.Best estimate of 60 × 61? (a) 36000 (b) 360 (c) 3600
  8. 8.Best estimate of 87 × 78? (a) 720 (b) 72000 (c) 7200
  9. 9.Best estimate of 666 + 772? (a) 1700 (b) 1500 (c) 1300
  10. 10.Best estimate of 159 + 544? (a) 900 (b) 700 (c) 500
  11. 11.Best estimate of 240 + 675? (a) 900 (b) 1100 (c) 700
  12. 12.Best estimate of 63 × 28? (a) 18000 (b) 180 (c) 1800
  13. 13.Best estimate of 431 + 183? (a) 600 (b) 400 (c) 800
  14. 14.Best estimate of 357 + 239? (a) 800 (b) 400 (c) 600
  15. 15.Best estimate of 49 × 43? (a) 200 (b) 20000 (c) 2000
  16. 16.Best estimate of 753 + 231? (a) 1200 (b) 1000 (c) 800
  17. 17.Best estimate of 83 × 27? (a) 240 (b) 2400 (c) 24000
  18. 18.Best estimate of 445 + 321? (a) 900 (b) 500 (c) 700
  19. 19.Best estimate of 12 × 14? (a) 10 (b) 100 (c) 1000
  20. 20.Best estimate of 96 × 42? (a) 40000 (b) 400 (c) 4000
  21. 21.Best estimate of 288 + 313? (a) 400 (b) 800 (c) 600
  22. 22.Best estimate of 256 + 742? (a) 1000 (b) 800 (c) 1200
  23. 23.Best estimate of 62 × 81? (a) 4800 (b) 480 (c) 48000
  24. 24.Best estimate of 86 × 16? (a) 18000 (b) 1800 (c) 180
  25. 25.Best estimate of 61 × 43? (a) 240 (b) 24000 (c) 2400
  26. 26.Best estimate of 487 + 825? (a) 1100 (b) 1500 (c) 1300
  27. 27.Best estimate of 279 + 803? (a) 1300 (b) 900 (c) 1100
  28. 28.Best estimate of 27 × 93? (a) 270 (b) 27000 (c) 2700
  29. 29.Best estimate of 94 × 88? (a) 8100 (b) 810 (c) 81000
  30. 30.Best estimate of 29 × 54? (a) 1500 (b) 150 (c) 15000
  31. 31.Best estimate of 823 + 234? (a) 1000 (b) 1200 (c) 800
  32. 32.Best estimate of 326 + 662? (a) 1000 (b) 1200 (c) 800
  33. 33.Best estimate of 74 × 88? (a) 63000 (b) 630 (c) 6300
  34. 34.Best estimate of 24 × 41? (a) 800 (b) 8000 (c) 80
  35. 35.Best estimate of 519 + 395? (a) 1100 (b) 700 (c) 900
  36. 36.Best estimate of 76 × 69? (a) 56000 (b) 560 (c) 5600
  37. 37.Best estimate of 32 × 24? (a) 60 (b) 6000 (c) 600
  38. 38.Best estimate of 359 + 744? (a) 1300 (b) 1100 (c) 900
  39. 39.Best estimate of 29 × 31? (a) 90 (b) 900 (c) 9000
  40. 40.Best estimate of 260 + 251? (a) 800 (b) 400 (c) 600

Answer key

  1. 1400
  2. 1600
  3. 1200
  4. 600
  5. 500
  6. 1400
  7. 3600
  8. 7200
  9. 1500
  10. 700
  11. 900
  12. 1800
  13. 600
  14. 600
  15. 2000
  16. 1000
  17. 2400
  18. 700
  19. 100
  20. 4000
  21. 600
  22. 1000
  23. 4800
  24. 1800
  25. 2400
  26. 1300
  27. 1100
  28. 2700
  29. 8100
  30. 1500
  31. 1000
  32. 1000
  33. 6300
  34. 800
  35. 900
  36. 5600
  37. 600
  38. 1100
  39. 900
  40. 600

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