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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 918 · 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 88 × 91? (a) 8100 (b) 81000 (c) 810
  2. 2.Best estimate of 46 × 20? (a) 1000 (b) 100 (c) 10000
  3. 3.Best estimate of 496 + 333? (a) 800 (b) 600 (c) 1000
  4. 4.Best estimate of 26 × 33? (a) 900 (b) 90 (c) 9000
  5. 5.Best estimate of 30 × 43? (a) 1200 (b) 120 (c) 12000
  6. 6.Best estimate of 670 + 560? (a) 1500 (b) 1300 (c) 1100
  7. 7.Best estimate of 69 × 66? (a) 4900 (b) 49000 (c) 490
  8. 8.Best estimate of 14 × 90? (a) 9000 (b) 900 (c) 90
  9. 9.Best estimate of 48 × 21? (a) 1000 (b) 10000 (c) 100
  10. 10.Best estimate of 91 × 91? (a) 8100 (b) 81000 (c) 810
  11. 11.Best estimate of 311 + 259? (a) 400 (b) 800 (c) 600
  12. 12.Best estimate of 676 + 380? (a) 900 (b) 1300 (c) 1100
  13. 13.Best estimate of 72 × 66? (a) 4900 (b) 49000 (c) 490
  14. 14.Best estimate of 13 × 77? (a) 8000 (b) 80 (c) 800
  15. 15.Best estimate of 26 × 87? (a) 27000 (b) 270 (c) 2700
  16. 16.Best estimate of 28 × 26? (a) 9000 (b) 90 (c) 900
  17. 17.Best estimate of 462 + 473? (a) 800 (b) 1200 (c) 1000
  18. 18.Best estimate of 67 × 22? (a) 140 (b) 1400 (c) 14000
  19. 19.Best estimate of 74 × 98? (a) 70000 (b) 7000 (c) 700
  20. 20.Best estimate of 332 + 646? (a) 700 (b) 1100 (c) 900
  21. 21.Best estimate of 813 + 838? (a) 1600 (b) 1800 (c) 1400
  22. 22.Best estimate of 131 + 540? (a) 600 (b) 400 (c) 800
  23. 23.Best estimate of 56 × 17? (a) 12000 (b) 120 (c) 1200
  24. 24.Best estimate of 641 + 611? (a) 1200 (b) 1000 (c) 1400
  25. 25.Best estimate of 64 × 46? (a) 3000 (b) 30000 (c) 300
  26. 26.Best estimate of 275 + 182? (a) 500 (b) 700 (c) 300
  27. 27.Best estimate of 701 + 193? (a) 1100 (b) 700 (c) 900
  28. 28.Best estimate of 42 × 18? (a) 8000 (b) 800 (c) 80
  29. 29.Best estimate of 339 + 507? (a) 1000 (b) 800 (c) 600
  30. 30.Best estimate of 42 × 28? (a) 120 (b) 12000 (c) 1200
  31. 31.Best estimate of 17 × 97? (a) 2000 (b) 200 (c) 20000
  32. 32.Best estimate of 159 + 262? (a) 700 (b) 500 (c) 300
  33. 33.Best estimate of 748 + 878? (a) 1600 (b) 1800 (c) 1400
  34. 34.Best estimate of 498 + 204? (a) 900 (b) 500 (c) 700
  35. 35.Best estimate of 50 × 36? (a) 2000 (b) 20000 (c) 200
  36. 36.Best estimate of 71 × 58? (a) 42000 (b) 420 (c) 4200
  37. 37.Best estimate of 432 + 289? (a) 700 (b) 500 (c) 900
  38. 38.Best estimate of 707 + 794? (a) 1700 (b) 1300 (c) 1500
  39. 39.Best estimate of 74 × 36? (a) 28000 (b) 2800 (c) 280
  40. 40.Best estimate of 239 + 163? (a) 600 (b) 200 (c) 400

Answer key

  1. 8100
  2. 1000
  3. 800
  4. 900
  5. 1200
  6. 1300
  7. 4900
  8. 900
  9. 1000
  10. 8100
  11. 600
  12. 1100
  13. 4900
  14. 800
  15. 2700
  16. 900
  17. 1000
  18. 1400
  19. 7000
  20. 900
  21. 1600
  22. 600
  23. 1200
  24. 1200
  25. 3000
  26. 500
  27. 900
  28. 800
  29. 800
  30. 1200
  31. 2000
  32. 500
  33. 1600
  34. 700
  35. 2000
  36. 4200
  37. 700
  38. 1500
  39. 2800
  40. 400

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