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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 461 · 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 43 × 21? (a) 80 (b) 8000 (c) 800
  2. 2.Best estimate of 89 × 43? (a) 3600 (b) 36000 (c) 360
  3. 3.Best estimate of 358 + 441? (a) 600 (b) 1000 (c) 800
  4. 4.Best estimate of 80 × 27? (a) 2400 (b) 24000 (c) 240
  5. 5.Best estimate of 78 × 41? (a) 3200 (b) 320 (c) 32000
  6. 6.Best estimate of 854 + 243? (a) 900 (b) 1300 (c) 1100
  7. 7.Best estimate of 809 + 513? (a) 1100 (b) 1500 (c) 1300
  8. 8.Best estimate of 34 × 41? (a) 1200 (b) 120 (c) 12000
  9. 9.Best estimate of 252 + 610? (a) 700 (b) 900 (c) 1100
  10. 10.Best estimate of 12 × 37? (a) 4000 (b) 400 (c) 40
  11. 11.Best estimate of 495 + 258? (a) 1000 (b) 800 (c) 600
  12. 12.Best estimate of 17 × 46? (a) 1000 (b) 10000 (c) 100
  13. 13.Best estimate of 497 + 465? (a) 800 (b) 1200 (c) 1000
  14. 14.Best estimate of 702 + 501? (a) 1000 (b) 1400 (c) 1200
  15. 15.Best estimate of 853 + 662? (a) 1600 (b) 1400 (c) 1800
  16. 16.Best estimate of 16 × 76? (a) 160 (b) 16000 (c) 1600
  17. 17.Best estimate of 496 + 687? (a) 1200 (b) 1400 (c) 1000
  18. 18.Best estimate of 563 + 592? (a) 1200 (b) 1400 (c) 1000
  19. 19.Best estimate of 171 + 203? (a) 200 (b) 400 (c) 600
  20. 20.Best estimate of 91 × 54? (a) 4500 (b) 45000 (c) 450
  21. 21.Best estimate of 654 + 469? (a) 1000 (b) 1400 (c) 1200
  22. 22.Best estimate of 654 + 320? (a) 1000 (b) 800 (c) 1200
  23. 23.Best estimate of 823 + 316? (a) 1300 (b) 1100 (c) 900
  24. 24.Best estimate of 197 + 234? (a) 600 (b) 400 (c) 200
  25. 25.Best estimate of 61 × 54? (a) 30000 (b) 3000 (c) 300
  26. 26.Best estimate of 199 + 243? (a) 200 (b) 600 (c) 400
  27. 27.Best estimate of 76 × 81? (a) 64000 (b) 6400 (c) 640
  28. 28.Best estimate of 638 + 209? (a) 600 (b) 800 (c) 1000
  29. 29.Best estimate of 306 + 121? (a) 600 (b) 200 (c) 400
  30. 30.Best estimate of 429 + 415? (a) 800 (b) 1000 (c) 600
  31. 31.Best estimate of 53 × 50? (a) 2500 (b) 250 (c) 25000
  32. 32.Best estimate of 79 × 72? (a) 5600 (b) 56000 (c) 560
  33. 33.Best estimate of 24 × 68? (a) 1400 (b) 140 (c) 14000
  34. 34.Best estimate of 330 + 821? (a) 1100 (b) 900 (c) 1300
  35. 35.Best estimate of 71 × 79? (a) 56000 (b) 560 (c) 5600
  36. 36.Best estimate of 18 × 26? (a) 60 (b) 600 (c) 6000
  37. 37.Best estimate of 851 + 395? (a) 1500 (b) 1300 (c) 1100
  38. 38.Best estimate of 96 × 57? (a) 60000 (b) 6000 (c) 600
  39. 39.Best estimate of 773 + 493? (a) 1500 (b) 1100 (c) 1300
  40. 40.Best estimate of 278 + 308? (a) 800 (b) 400 (c) 600

Answer key

  1. 800
  2. 3600
  3. 800
  4. 2400
  5. 3200
  6. 1100
  7. 1300
  8. 1200
  9. 900
  10. 400
  11. 800
  12. 1000
  13. 1000
  14. 1200
  15. 1600
  16. 1600
  17. 1200
  18. 1200
  19. 400
  20. 4500
  21. 1200
  22. 1000
  23. 1100
  24. 400
  25. 3000
  26. 400
  27. 6400
  28. 800
  29. 400
  30. 800
  31. 2500
  32. 5600
  33. 1400
  34. 1100
  35. 5600
  36. 600
  37. 1300
  38. 6000
  39. 1300
  40. 600

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