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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 231 · 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 16 × 39? (a) 800 (b) 8000 (c) 80
  2. 2.Best estimate of 96 × 20? (a) 200 (b) 2000 (c) 20000
  3. 3.Best estimate of 139 + 274? (a) 600 (b) 200 (c) 400
  4. 4.Best estimate of 42 × 64? (a) 24000 (b) 2400 (c) 240
  5. 5.Best estimate of 275 + 878? (a) 1400 (b) 1000 (c) 1200
  6. 6.Best estimate of 481 + 355? (a) 900 (b) 700 (c) 1100
  7. 7.Best estimate of 797 + 404? (a) 1400 (b) 1200 (c) 1000
  8. 8.Best estimate of 87 × 86? (a) 81000 (b) 8100 (c) 810
  9. 9.Best estimate of 462 + 337? (a) 600 (b) 1000 (c) 800
  10. 10.Best estimate of 591 + 734? (a) 1500 (b) 1100 (c) 1300
  11. 11.Best estimate of 37 × 98? (a) 40000 (b) 4000 (c) 400
  12. 12.Best estimate of 225 + 694? (a) 1100 (b) 700 (c) 900
  13. 13.Best estimate of 459 + 564? (a) 1100 (b) 1300 (c) 900
  14. 14.Best estimate of 864 + 841? (a) 1500 (b) 1700 (c) 1900
  15. 15.Best estimate of 376 + 216? (a) 400 (b) 800 (c) 600
  16. 16.Best estimate of 435 + 664? (a) 1100 (b) 1300 (c) 900
  17. 17.Best estimate of 459 + 341? (a) 1000 (b) 800 (c) 600
  18. 18.Best estimate of 91 × 36? (a) 36000 (b) 3600 (c) 360
  19. 19.Best estimate of 60 × 83? (a) 4800 (b) 480 (c) 48000
  20. 20.Best estimate of 555 + 419? (a) 1000 (b) 1200 (c) 800
  21. 21.Best estimate of 121 + 189? (a) 500 (b) 300 (c) 100
  22. 22.Best estimate of 44 × 24? (a) 80 (b) 8000 (c) 800
  23. 23.Best estimate of 270 + 689? (a) 1000 (b) 1200 (c) 800
  24. 24.Best estimate of 68 × 43? (a) 2800 (b) 28000 (c) 280
  25. 25.Best estimate of 37 × 57? (a) 240 (b) 2400 (c) 24000
  26. 26.Best estimate of 57 × 64? (a) 36000 (b) 3600 (c) 360
  27. 27.Best estimate of 41 × 18? (a) 800 (b) 8000 (c) 80
  28. 28.Best estimate of 59 × 22? (a) 120 (b) 1200 (c) 12000
  29. 29.Best estimate of 443 + 507? (a) 700 (b) 1100 (c) 900
  30. 30.Best estimate of 529 + 261? (a) 1000 (b) 600 (c) 800
  31. 31.Best estimate of 526 + 192? (a) 700 (b) 500 (c) 900
  32. 32.Best estimate of 23 × 43? (a) 800 (b) 80 (c) 8000
  33. 33.Best estimate of 96 × 56? (a) 60000 (b) 600 (c) 6000
  34. 34.Best estimate of 233 + 621? (a) 800 (b) 1000 (c) 600
  35. 35.Best estimate of 819 + 269? (a) 1300 (b) 900 (c) 1100
  36. 36.Best estimate of 327 + 122? (a) 200 (b) 400 (c) 600
  37. 37.Best estimate of 63 × 28? (a) 180 (b) 1800 (c) 18000
  38. 38.Best estimate of 149 + 176? (a) 300 (b) 500 (c) 100
  39. 39.Best estimate of 806 + 416? (a) 1200 (b) 1000 (c) 1400
  40. 40.Best estimate of 633 + 676? (a) 1100 (b) 1500 (c) 1300

Answer key

  1. 800
  2. 2000
  3. 400
  4. 2400
  5. 1200
  6. 900
  7. 1200
  8. 8100
  9. 800
  10. 1300
  11. 4000
  12. 900
  13. 1100
  14. 1700
  15. 600
  16. 1100
  17. 800
  18. 3600
  19. 4800
  20. 1000
  21. 300
  22. 800
  23. 1000
  24. 2800
  25. 2400
  26. 3600
  27. 800
  28. 1200
  29. 900
  30. 800
  31. 700
  32. 800
  33. 6000
  34. 800
  35. 1100
  36. 400
  37. 1800
  38. 300
  39. 1200
  40. 1300

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