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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 309 · 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 53 × 18? (a) 100 (b) 1000 (c) 10000
  2. 2.Best estimate of 192 + 597? (a) 600 (b) 1000 (c) 800
  3. 3.Best estimate of 268 + 614? (a) 700 (b) 1100 (c) 900
  4. 4.Best estimate of 176 + 372? (a) 400 (b) 600 (c) 800
  5. 5.Best estimate of 221 + 223? (a) 600 (b) 200 (c) 400
  6. 6.Best estimate of 12 × 32? (a) 300 (b) 30 (c) 3000
  7. 7.Best estimate of 168 + 407? (a) 600 (b) 400 (c) 800
  8. 8.Best estimate of 316 + 204? (a) 300 (b) 700 (c) 500
  9. 9.Best estimate of 43 × 87? (a) 36000 (b) 3600 (c) 360
  10. 10.Best estimate of 96 × 47? (a) 5000 (b) 500 (c) 50000
  11. 11.Best estimate of 364 + 580? (a) 800 (b) 1200 (c) 1000
  12. 12.Best estimate of 874 + 296? (a) 1000 (b) 1200 (c) 1400
  13. 13.Best estimate of 31 × 37? (a) 12000 (b) 1200 (c) 120
  14. 14.Best estimate of 180 + 275? (a) 700 (b) 300 (c) 500
  15. 15.Best estimate of 66 × 91? (a) 6300 (b) 630 (c) 63000
  16. 16.Best estimate of 37 × 46? (a) 2000 (b) 200 (c) 20000
  17. 17.Best estimate of 22 × 62? (a) 12000 (b) 1200 (c) 120
  18. 18.Best estimate of 870 + 375? (a) 1300 (b) 1100 (c) 1500
  19. 19.Best estimate of 51 × 91? (a) 4500 (b) 450 (c) 45000
  20. 20.Best estimate of 381 + 614? (a) 1200 (b) 800 (c) 1000
  21. 21.Best estimate of 226 + 807? (a) 1000 (b) 1200 (c) 800
  22. 22.Best estimate of 78 × 92? (a) 7200 (b) 72000 (c) 720
  23. 23.Best estimate of 328 + 791? (a) 1100 (b) 900 (c) 1300
  24. 24.Best estimate of 68 × 32? (a) 210 (b) 2100 (c) 21000
  25. 25.Best estimate of 31 × 20? (a) 600 (b) 6000 (c) 60
  26. 26.Best estimate of 782 + 678? (a) 1700 (b) 1500 (c) 1300
  27. 27.Best estimate of 29 × 18? (a) 600 (b) 6000 (c) 60
  28. 28.Best estimate of 76 × 83? (a) 64000 (b) 6400 (c) 640
  29. 29.Best estimate of 46 × 43? (a) 20000 (b) 200 (c) 2000
  30. 30.Best estimate of 324 + 153? (a) 300 (b) 700 (c) 500
  31. 31.Best estimate of 77 × 71? (a) 560 (b) 56000 (c) 5600
  32. 32.Best estimate of 515 + 751? (a) 1500 (b) 1100 (c) 1300
  33. 33.Best estimate of 295 + 327? (a) 400 (b) 600 (c) 800
  34. 34.Best estimate of 14 × 97? (a) 100 (b) 10000 (c) 1000
  35. 35.Best estimate of 508 + 815? (a) 1500 (b) 1300 (c) 1100
  36. 36.Best estimate of 149 + 723? (a) 800 (b) 1000 (c) 600
  37. 37.Best estimate of 334 + 748? (a) 800 (b) 1200 (c) 1000
  38. 38.Best estimate of 29 × 96? (a) 3000 (b) 300 (c) 30000
  39. 39.Best estimate of 611 + 405? (a) 800 (b) 1000 (c) 1200
  40. 40.Best estimate of 343 + 867? (a) 1400 (b) 1000 (c) 1200

Answer key

  1. 1000
  2. 800
  3. 900
  4. 600
  5. 400
  6. 300
  7. 600
  8. 500
  9. 3600
  10. 5000
  11. 1000
  12. 1200
  13. 1200
  14. 500
  15. 6300
  16. 2000
  17. 1200
  18. 1300
  19. 4500
  20. 1000
  21. 1000
  22. 7200
  23. 1100
  24. 2100
  25. 600
  26. 1500
  27. 600
  28. 6400
  29. 2000
  30. 500
  31. 5600
  32. 1300
  33. 600
  34. 1000
  35. 1300
  36. 800
  37. 1000
  38. 3000
  39. 1000
  40. 1200

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