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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 315 · 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 307 + 233? (a) 500 (b) 300 (c) 700
  2. 2.Best estimate of 244 + 698? (a) 900 (b) 700 (c) 1100
  3. 3.Best estimate of 652 + 310? (a) 1000 (b) 800 (c) 1200
  4. 4.Best estimate of 338 + 415? (a) 900 (b) 700 (c) 500
  5. 5.Best estimate of 42 × 26? (a) 120 (b) 1200 (c) 12000
  6. 6.Best estimate of 226 + 193? (a) 600 (b) 400 (c) 200
  7. 7.Best estimate of 32 × 59? (a) 18000 (b) 1800 (c) 180
  8. 8.Best estimate of 403 + 438? (a) 800 (b) 1000 (c) 600
  9. 9.Best estimate of 38 × 13? (a) 400 (b) 4000 (c) 40
  10. 10.Best estimate of 26 × 66? (a) 210 (b) 2100 (c) 21000
  11. 11.Best estimate of 712 + 605? (a) 1300 (b) 1100 (c) 1500
  12. 12.Best estimate of 570 + 289? (a) 900 (b) 1100 (c) 700
  13. 13.Best estimate of 50 × 16? (a) 10000 (b) 1000 (c) 100
  14. 14.Best estimate of 733 + 306? (a) 1200 (b) 1000 (c) 800
  15. 15.Best estimate of 466 + 236? (a) 700 (b) 900 (c) 500
  16. 16.Best estimate of 471 + 471? (a) 1200 (b) 1000 (c) 800
  17. 17.Best estimate of 132 + 449? (a) 500 (b) 700 (c) 300
  18. 18.Best estimate of 20 × 53? (a) 1000 (b) 10000 (c) 100
  19. 19.Best estimate of 79 × 67? (a) 5600 (b) 56000 (c) 560
  20. 20.Best estimate of 711 + 448? (a) 1300 (b) 900 (c) 1100
  21. 21.Best estimate of 586 + 497? (a) 1100 (b) 1300 (c) 900
  22. 22.Best estimate of 13 × 47? (a) 5000 (b) 500 (c) 50
  23. 23.Best estimate of 76 × 96? (a) 800 (b) 80000 (c) 8000
  24. 24.Best estimate of 385 + 469? (a) 1100 (b) 900 (c) 700
  25. 25.Best estimate of 56 × 31? (a) 1800 (b) 18000 (c) 180
  26. 26.Best estimate of 352 + 761? (a) 1000 (b) 1400 (c) 1200
  27. 27.Best estimate of 33 × 29? (a) 9000 (b) 90 (c) 900
  28. 28.Best estimate of 716 + 557? (a) 1300 (b) 1100 (c) 1500
  29. 29.Best estimate of 77 × 96? (a) 8000 (b) 80000 (c) 800
  30. 30.Best estimate of 82 × 92? (a) 7200 (b) 720 (c) 72000
  31. 31.Best estimate of 98 × 31? (a) 30000 (b) 300 (c) 3000
  32. 32.Best estimate of 429 + 353? (a) 800 (b) 1000 (c) 600
  33. 33.Best estimate of 160 + 134? (a) 500 (b) 100 (c) 300
  34. 34.Best estimate of 828 + 167? (a) 1000 (b) 800 (c) 1200
  35. 35.Best estimate of 70 × 21? (a) 1400 (b) 14000 (c) 140
  36. 36.Best estimate of 39 × 67? (a) 2800 (b) 280 (c) 28000
  37. 37.Best estimate of 98 × 50? (a) 500 (b) 50000 (c) 5000
  38. 38.Best estimate of 14 × 78? (a) 800 (b) 8000 (c) 80
  39. 39.Best estimate of 47 × 26? (a) 1500 (b) 150 (c) 15000
  40. 40.Best estimate of 365 + 372? (a) 600 (b) 1000 (c) 800

Answer key

  1. 500
  2. 900
  3. 1000
  4. 700
  5. 1200
  6. 400
  7. 1800
  8. 800
  9. 400
  10. 2100
  11. 1300
  12. 900
  13. 1000
  14. 1000
  15. 700
  16. 1000
  17. 500
  18. 1000
  19. 5600
  20. 1100
  21. 1100
  22. 500
  23. 8000
  24. 900
  25. 1800
  26. 1200
  27. 900
  28. 1300
  29. 8000
  30. 7200
  31. 3000
  32. 800
  33. 300
  34. 1000
  35. 1400
  36. 2800
  37. 5000
  38. 800
  39. 1500
  40. 800

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