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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 71 · 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 838 + 181? (a) 1200 (b) 1000 (c) 800
  2. 2.Best estimate of 90 × 14? (a) 90 (b) 9000 (c) 900
  3. 3.Best estimate of 21 × 20? (a) 4000 (b) 400 (c) 40
  4. 4.Best estimate of 771 + 657? (a) 1500 (b) 1300 (c) 1700
  5. 5.Best estimate of 82 × 93? (a) 72000 (b) 720 (c) 7200
  6. 6.Best estimate of 84 × 84? (a) 640 (b) 6400 (c) 64000
  7. 7.Best estimate of 80 × 96? (a) 80000 (b) 8000 (c) 800
  8. 8.Best estimate of 498 + 669? (a) 1400 (b) 1200 (c) 1000
  9. 9.Best estimate of 780 + 509? (a) 1500 (b) 1300 (c) 1100
  10. 10.Best estimate of 93 × 24? (a) 1800 (b) 180 (c) 18000
  11. 11.Best estimate of 362 + 433? (a) 600 (b) 1000 (c) 800
  12. 12.Best estimate of 369 + 717? (a) 900 (b) 1100 (c) 1300
  13. 13.Best estimate of 377 + 863? (a) 1300 (b) 1100 (c) 1500
  14. 14.Best estimate of 781 + 486? (a) 1300 (b) 1500 (c) 1100
  15. 15.Best estimate of 303 + 462? (a) 800 (b) 1000 (c) 600
  16. 16.Best estimate of 719 + 460? (a) 1400 (b) 1000 (c) 1200
  17. 17.Best estimate of 511 + 145? (a) 800 (b) 600 (c) 400
  18. 18.Best estimate of 66 × 76? (a) 56000 (b) 5600 (c) 560
  19. 19.Best estimate of 226 + 568? (a) 800 (b) 1000 (c) 600
  20. 20.Best estimate of 42 × 22? (a) 80 (b) 8000 (c) 800
  21. 21.Best estimate of 742 + 766? (a) 1300 (b) 1700 (c) 1500
  22. 22.Best estimate of 48 × 66? (a) 3500 (b) 35000 (c) 350
  23. 23.Best estimate of 186 + 535? (a) 700 (b) 500 (c) 900
  24. 24.Best estimate of 220 + 627? (a) 600 (b) 800 (c) 1000
  25. 25.Best estimate of 92 × 94? (a) 810 (b) 8100 (c) 81000
  26. 26.Best estimate of 94 × 84? (a) 720 (b) 7200 (c) 72000
  27. 27.Best estimate of 828 + 719? (a) 1700 (b) 1300 (c) 1500
  28. 28.Best estimate of 86 × 47? (a) 450 (b) 4500 (c) 45000
  29. 29.Best estimate of 535 + 408? (a) 900 (b) 1100 (c) 700
  30. 30.Best estimate of 87 × 54? (a) 4500 (b) 45000 (c) 450
  31. 31.Best estimate of 47 × 23? (a) 10000 (b) 100 (c) 1000
  32. 32.Best estimate of 621 + 538? (a) 1300 (b) 900 (c) 1100
  33. 33.Best estimate of 98 × 53? (a) 500 (b) 50000 (c) 5000
  34. 34.Best estimate of 179 + 507? (a) 900 (b) 700 (c) 500
  35. 35.Best estimate of 480 + 216? (a) 500 (b) 700 (c) 900
  36. 36.Best estimate of 194 + 749? (a) 900 (b) 700 (c) 1100
  37. 37.Best estimate of 286 + 244? (a) 500 (b) 300 (c) 700
  38. 38.Best estimate of 83 × 33? (a) 2400 (b) 240 (c) 24000
  39. 39.Best estimate of 572 + 128? (a) 700 (b) 900 (c) 500
  40. 40.Best estimate of 704 + 414? (a) 900 (b) 1100 (c) 1300

Answer key

  1. 1000
  2. 900
  3. 400
  4. 1500
  5. 7200
  6. 6400
  7. 8000
  8. 1200
  9. 1300
  10. 1800
  11. 800
  12. 1100
  13. 1300
  14. 1300
  15. 800
  16. 1200
  17. 600
  18. 5600
  19. 800
  20. 800
  21. 1500
  22. 3500
  23. 700
  24. 800
  25. 8100
  26. 7200
  27. 1500
  28. 4500
  29. 900
  30. 4500
  31. 1000
  32. 1100
  33. 5000
  34. 700
  35. 700
  36. 900
  37. 500
  38. 2400
  39. 700
  40. 1100

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