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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 476 · 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 69 × 23? (a) 1400 (b) 14000 (c) 140
  2. 2.Best estimate of 226 + 573? (a) 600 (b) 1000 (c) 800
  3. 3.Best estimate of 221 + 629? (a) 1000 (b) 800 (c) 600
  4. 4.Best estimate of 80 × 41? (a) 32000 (b) 320 (c) 3200
  5. 5.Best estimate of 775 + 221? (a) 1200 (b) 1000 (c) 800
  6. 6.Best estimate of 241 + 721? (a) 900 (b) 1100 (c) 700
  7. 7.Best estimate of 69 × 27? (a) 210 (b) 2100 (c) 21000
  8. 8.Best estimate of 43 × 80? (a) 32000 (b) 320 (c) 3200
  9. 9.Best estimate of 49 × 17? (a) 10000 (b) 1000 (c) 100
  10. 10.Best estimate of 232 + 791? (a) 1000 (b) 800 (c) 1200
  11. 11.Best estimate of 640 + 229? (a) 600 (b) 800 (c) 1000
  12. 12.Best estimate of 39 × 72? (a) 280 (b) 2800 (c) 28000
  13. 13.Best estimate of 473 + 654? (a) 1000 (b) 1200 (c) 1400
  14. 14.Best estimate of 778 + 700? (a) 1700 (b) 1500 (c) 1300
  15. 15.Best estimate of 26 × 66? (a) 21000 (b) 210 (c) 2100
  16. 16.Best estimate of 32 × 96? (a) 300 (b) 3000 (c) 30000
  17. 17.Best estimate of 469 + 784? (a) 1100 (b) 1500 (c) 1300
  18. 18.Best estimate of 621 + 327? (a) 1100 (b) 700 (c) 900
  19. 19.Best estimate of 726 + 666? (a) 1400 (b) 1600 (c) 1200
  20. 20.Best estimate of 272 + 226? (a) 500 (b) 700 (c) 300
  21. 21.Best estimate of 83 × 83? (a) 640 (b) 64000 (c) 6400
  22. 22.Best estimate of 782 + 451? (a) 1300 (b) 1500 (c) 1100
  23. 23.Best estimate of 227 + 170? (a) 600 (b) 200 (c) 400
  24. 24.Best estimate of 31 × 20? (a) 60 (b) 600 (c) 6000
  25. 25.Best estimate of 877 + 291? (a) 1400 (b) 1200 (c) 1000
  26. 26.Best estimate of 26 × 87? (a) 270 (b) 27000 (c) 2700
  27. 27.Best estimate of 20 × 46? (a) 10000 (b) 100 (c) 1000
  28. 28.Best estimate of 234 + 665? (a) 700 (b) 900 (c) 1100
  29. 29.Best estimate of 16 × 44? (a) 8000 (b) 800 (c) 80
  30. 30.Best estimate of 248 + 368? (a) 400 (b) 600 (c) 800
  31. 31.Best estimate of 702 + 242? (a) 700 (b) 900 (c) 1100
  32. 32.Best estimate of 24 × 32? (a) 600 (b) 60 (c) 6000
  33. 33.Best estimate of 66 × 37? (a) 28000 (b) 280 (c) 2800
  34. 34.Best estimate of 42 × 22? (a) 800 (b) 80 (c) 8000
  35. 35.Best estimate of 71 × 60? (a) 420 (b) 42000 (c) 4200
  36. 36.Best estimate of 207 + 186? (a) 600 (b) 400 (c) 200
  37. 37.Best estimate of 246 + 366? (a) 800 (b) 600 (c) 400
  38. 38.Best estimate of 36 × 50? (a) 20000 (b) 200 (c) 2000
  39. 39.Best estimate of 504 + 476? (a) 1200 (b) 800 (c) 1000
  40. 40.Best estimate of 19 × 72? (a) 1400 (b) 140 (c) 14000

Answer key

  1. 1400
  2. 800
  3. 800
  4. 3200
  5. 1000
  6. 900
  7. 2100
  8. 3200
  9. 1000
  10. 1000
  11. 800
  12. 2800
  13. 1200
  14. 1500
  15. 2100
  16. 3000
  17. 1300
  18. 900
  19. 1400
  20. 500
  21. 6400
  22. 1300
  23. 400
  24. 600
  25. 1200
  26. 2700
  27. 1000
  28. 900
  29. 800
  30. 600
  31. 900
  32. 600
  33. 2800
  34. 800
  35. 4200
  36. 400
  37. 600
  38. 2000
  39. 1000
  40. 1400

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