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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 950 · 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 187 + 124? (a) 100 (b) 300 (c) 500
  2. 2.Best estimate of 869 + 444? (a) 1300 (b) 1100 (c) 1500
  3. 3.Best estimate of 31 × 66? (a) 210 (b) 2100 (c) 21000
  4. 4.Best estimate of 240 + 321? (a) 300 (b) 500 (c) 700
  5. 5.Best estimate of 275 + 812? (a) 900 (b) 1100 (c) 1300
  6. 6.Best estimate of 167 + 479? (a) 500 (b) 900 (c) 700
  7. 7.Best estimate of 46 × 94? (a) 4500 (b) 45000 (c) 450
  8. 8.Best estimate of 36 × 89? (a) 36000 (b) 360 (c) 3600
  9. 9.Best estimate of 499 + 206? (a) 700 (b) 500 (c) 900
  10. 10.Best estimate of 304 + 443? (a) 900 (b) 500 (c) 700
  11. 11.Best estimate of 200 + 357? (a) 800 (b) 600 (c) 400
  12. 12.Best estimate of 14 × 26? (a) 3000 (b) 30 (c) 300
  13. 13.Best estimate of 51 × 12? (a) 500 (b) 5000 (c) 50
  14. 14.Best estimate of 477 + 616? (a) 1100 (b) 1300 (c) 900
  15. 15.Best estimate of 39 × 14? (a) 40 (b) 4000 (c) 400
  16. 16.Best estimate of 723 + 247? (a) 1100 (b) 900 (c) 700
  17. 17.Best estimate of 590 + 227? (a) 600 (b) 1000 (c) 800
  18. 18.Best estimate of 600 + 366? (a) 1000 (b) 800 (c) 1200
  19. 19.Best estimate of 61 × 78? (a) 480 (b) 4800 (c) 48000
  20. 20.Best estimate of 36 × 61? (a) 2400 (b) 24000 (c) 240
  21. 21.Best estimate of 652 + 131? (a) 1000 (b) 800 (c) 600
  22. 22.Best estimate of 30 × 36? (a) 12000 (b) 120 (c) 1200
  23. 23.Best estimate of 92 × 37? (a) 36000 (b) 360 (c) 3600
  24. 24.Best estimate of 91 × 70? (a) 630 (b) 63000 (c) 6300
  25. 25.Best estimate of 809 + 578? (a) 1600 (b) 1200 (c) 1400
  26. 26.Best estimate of 431 + 219? (a) 600 (b) 400 (c) 800
  27. 27.Best estimate of 354 + 862? (a) 1500 (b) 1100 (c) 1300
  28. 28.Best estimate of 464 + 498? (a) 1000 (b) 1200 (c) 800
  29. 29.Best estimate of 76 × 56? (a) 4800 (b) 48000 (c) 480
  30. 30.Best estimate of 46 × 89? (a) 45000 (b) 4500 (c) 450
  31. 31.Best estimate of 220 + 723? (a) 900 (b) 700 (c) 1100
  32. 32.Best estimate of 77 × 82? (a) 640 (b) 64000 (c) 6400
  33. 33.Best estimate of 342 + 337? (a) 600 (b) 800 (c) 400
  34. 34.Best estimate of 90 × 53? (a) 4500 (b) 450 (c) 45000
  35. 35.Best estimate of 20 × 46? (a) 100 (b) 1000 (c) 10000
  36. 36.Best estimate of 79 × 66? (a) 5600 (b) 560 (c) 56000
  37. 37.Best estimate of 205 + 133? (a) 500 (b) 100 (c) 300
  38. 38.Best estimate of 865 + 837? (a) 1700 (b) 1500 (c) 1900
  39. 39.Best estimate of 649 + 231? (a) 1000 (b) 600 (c) 800
  40. 40.Best estimate of 26 × 26? (a) 900 (b) 9000 (c) 90

Answer key

  1. 300
  2. 1300
  3. 2100
  4. 500
  5. 1100
  6. 700
  7. 4500
  8. 3600
  9. 700
  10. 700
  11. 600
  12. 300
  13. 500
  14. 1100
  15. 400
  16. 900
  17. 800
  18. 1000
  19. 4800
  20. 2400
  21. 800
  22. 1200
  23. 3600
  24. 6300
  25. 1400
  26. 600
  27. 1300
  28. 1000
  29. 4800
  30. 4500
  31. 900
  32. 6400
  33. 600
  34. 4500
  35. 1000
  36. 5600
  37. 300
  38. 1700
  39. 800
  40. 900

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