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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 472 · 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 257 + 509? (a) 600 (b) 1000 (c) 800
  2. 2.Best estimate of 638 + 153? (a) 800 (b) 600 (c) 1000
  3. 3.Best estimate of 683 + 704? (a) 1400 (b) 1200 (c) 1600
  4. 4.Best estimate of 56 × 20? (a) 120 (b) 1200 (c) 12000
  5. 5.Best estimate of 46 × 18? (a) 100 (b) 10000 (c) 1000
  6. 6.Best estimate of 70 × 62? (a) 4200 (b) 42000 (c) 420
  7. 7.Best estimate of 27 × 33? (a) 9000 (b) 900 (c) 90
  8. 8.Best estimate of 270 + 741? (a) 1200 (b) 800 (c) 1000
  9. 9.Best estimate of 381 + 568? (a) 1000 (b) 1200 (c) 800
  10. 10.Best estimate of 66 × 52? (a) 3500 (b) 35000 (c) 350
  11. 11.Best estimate of 601 + 646? (a) 1000 (b) 1200 (c) 1400
  12. 12.Best estimate of 26 × 66? (a) 210 (b) 21000 (c) 2100
  13. 13.Best estimate of 413 + 197? (a) 600 (b) 400 (c) 800
  14. 14.Best estimate of 38 × 23? (a) 800 (b) 8000 (c) 80
  15. 15.Best estimate of 16 × 61? (a) 12000 (b) 1200 (c) 120
  16. 16.Best estimate of 60 × 38? (a) 2400 (b) 240 (c) 24000
  17. 17.Best estimate of 218 + 370? (a) 600 (b) 400 (c) 800
  18. 18.Best estimate of 61 × 31? (a) 1800 (b) 18000 (c) 180
  19. 19.Best estimate of 46 × 27? (a) 1500 (b) 15000 (c) 150
  20. 20.Best estimate of 34 × 34? (a) 9000 (b) 900 (c) 90
  21. 21.Best estimate of 173 + 535? (a) 900 (b) 500 (c) 700
  22. 22.Best estimate of 644 + 865? (a) 1700 (b) 1300 (c) 1500
  23. 23.Best estimate of 53 × 41? (a) 20000 (b) 200 (c) 2000
  24. 24.Best estimate of 70 × 69? (a) 4900 (b) 49000 (c) 490
  25. 25.Best estimate of 19 × 92? (a) 18000 (b) 1800 (c) 180
  26. 26.Best estimate of 196 + 208? (a) 400 (b) 200 (c) 600
  27. 27.Best estimate of 749 + 726? (a) 1200 (b) 1600 (c) 1400
  28. 28.Best estimate of 93 × 12? (a) 900 (b) 90 (c) 9000
  29. 29.Best estimate of 241 + 316? (a) 300 (b) 700 (c) 500
  30. 30.Best estimate of 430 + 791? (a) 1200 (b) 1400 (c) 1000
  31. 31.Best estimate of 312 + 614? (a) 1100 (b) 900 (c) 700
  32. 32.Best estimate of 410 + 465? (a) 1100 (b) 900 (c) 700
  33. 33.Best estimate of 281 + 279? (a) 600 (b) 800 (c) 400
  34. 34.Best estimate of 57 × 39? (a) 240 (b) 2400 (c) 24000
  35. 35.Best estimate of 164 + 270? (a) 500 (b) 300 (c) 700
  36. 36.Best estimate of 691 + 388? (a) 1100 (b) 1300 (c) 900
  37. 37.Best estimate of 80 × 83? (a) 6400 (b) 64000 (c) 640
  38. 38.Best estimate of 333 + 206? (a) 700 (b) 500 (c) 300
  39. 39.Best estimate of 70 × 23? (a) 14000 (b) 1400 (c) 140
  40. 40.Best estimate of 719 + 861? (a) 1600 (b) 1800 (c) 1400

Answer key

  1. 800
  2. 800
  3. 1400
  4. 1200
  5. 1000
  6. 4200
  7. 900
  8. 1000
  9. 1000
  10. 3500
  11. 1200
  12. 2100
  13. 600
  14. 800
  15. 1200
  16. 2400
  17. 600
  18. 1800
  19. 1500
  20. 900
  21. 700
  22. 1500
  23. 2000
  24. 4900
  25. 1800
  26. 400
  27. 1400
  28. 900
  29. 500
  30. 1200
  31. 900
  32. 900
  33. 600
  34. 2400
  35. 500
  36. 1100
  37. 6400
  38. 500
  39. 1400
  40. 1600

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