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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 980 · 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 86 × 78? (a) 72000 (b) 720 (c) 7200
  2. 2.Best estimate of 72 × 61? (a) 420 (b) 42000 (c) 4200
  3. 3.Best estimate of 61 × 63? (a) 360 (b) 3600 (c) 36000
  4. 4.Best estimate of 27 × 36? (a) 1200 (b) 12000 (c) 120
  5. 5.Best estimate of 88 × 89? (a) 81000 (b) 810 (c) 8100
  6. 6.Best estimate of 202 + 427? (a) 600 (b) 800 (c) 400
  7. 7.Best estimate of 34 × 59? (a) 180 (b) 18000 (c) 1800
  8. 8.Best estimate of 868 + 856? (a) 2000 (b) 1600 (c) 1800
  9. 9.Best estimate of 66 × 26? (a) 2100 (b) 210 (c) 21000
  10. 10.Best estimate of 68 × 31? (a) 210 (b) 2100 (c) 21000
  11. 11.Best estimate of 92 × 57? (a) 54000 (b) 5400 (c) 540
  12. 12.Best estimate of 81 × 74? (a) 560 (b) 5600 (c) 56000
  13. 13.Best estimate of 82 × 47? (a) 400 (b) 40000 (c) 4000
  14. 14.Best estimate of 72 × 66? (a) 4900 (b) 490 (c) 49000
  15. 15.Best estimate of 56 × 56? (a) 36000 (b) 3600 (c) 360
  16. 16.Best estimate of 14 × 40? (a) 40 (b) 400 (c) 4000
  17. 17.Best estimate of 97 × 49? (a) 50000 (b) 5000 (c) 500
  18. 18.Best estimate of 353 + 498? (a) 900 (b) 1100 (c) 700
  19. 19.Best estimate of 228 + 136? (a) 300 (b) 100 (c) 500
  20. 20.Best estimate of 338 + 181? (a) 700 (b) 300 (c) 500
  21. 21.Best estimate of 64 × 47? (a) 300 (b) 3000 (c) 30000
  22. 22.Best estimate of 287 + 767? (a) 1100 (b) 1300 (c) 900
  23. 23.Best estimate of 335 + 853? (a) 1000 (b) 1200 (c) 1400
  24. 24.Best estimate of 97 × 39? (a) 40000 (b) 4000 (c) 400
  25. 25.Best estimate of 96 × 86? (a) 90000 (b) 900 (c) 9000
  26. 26.Best estimate of 236 + 719? (a) 700 (b) 1100 (c) 900
  27. 27.Best estimate of 705 + 171? (a) 900 (b) 1100 (c) 700
  28. 28.Best estimate of 84 × 12? (a) 80 (b) 8000 (c) 800
  29. 29.Best estimate of 624 + 576? (a) 1400 (b) 1000 (c) 1200
  30. 30.Best estimate of 92 × 17? (a) 1800 (b) 180 (c) 18000
  31. 31.Best estimate of 16 × 92? (a) 18000 (b) 180 (c) 1800
  32. 32.Best estimate of 36 × 51? (a) 20000 (b) 2000 (c) 200
  33. 33.Best estimate of 98 × 47? (a) 500 (b) 50000 (c) 5000
  34. 34.Best estimate of 76 × 74? (a) 5600 (b) 56000 (c) 560
  35. 35.Best estimate of 56 × 67? (a) 420 (b) 4200 (c) 42000
  36. 36.Best estimate of 548 + 809? (a) 1500 (b) 1100 (c) 1300
  37. 37.Best estimate of 235 + 487? (a) 700 (b) 900 (c) 500
  38. 38.Best estimate of 96 × 47? (a) 50000 (b) 5000 (c) 500
  39. 39.Best estimate of 42 × 27? (a) 120 (b) 12000 (c) 1200
  40. 40.Best estimate of 56 × 86? (a) 5400 (b) 54000 (c) 540

Answer key

  1. 7200
  2. 4200
  3. 3600
  4. 1200
  5. 8100
  6. 600
  7. 1800
  8. 1800
  9. 2100
  10. 2100
  11. 5400
  12. 5600
  13. 4000
  14. 4900
  15. 3600
  16. 400
  17. 5000
  18. 900
  19. 300
  20. 500
  21. 3000
  22. 1100
  23. 1200
  24. 4000
  25. 9000
  26. 900
  27. 900
  28. 800
  29. 1200
  30. 1800
  31. 1800
  32. 2000
  33. 5000
  34. 5600
  35. 4200
  36. 1300
  37. 700
  38. 5000
  39. 1200
  40. 5400

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