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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 793 · 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 783 + 869? (a) 1900 (b) 1500 (c) 1700
  2. 2.Best estimate of 820 + 869? (a) 1900 (b) 1500 (c) 1700
  3. 3.Best estimate of 796 + 854? (a) 1900 (b) 1500 (c) 1700
  4. 4.Best estimate of 48 × 30? (a) 15000 (b) 1500 (c) 150
  5. 5.Best estimate of 202 + 708? (a) 1100 (b) 900 (c) 700
  6. 6.Best estimate of 40 × 97? (a) 4000 (b) 400 (c) 40000
  7. 7.Best estimate of 24 × 91? (a) 18000 (b) 1800 (c) 180
  8. 8.Best estimate of 717 + 499? (a) 1000 (b) 1200 (c) 1400
  9. 9.Best estimate of 212 + 146? (a) 500 (b) 100 (c) 300
  10. 10.Best estimate of 22 × 31? (a) 600 (b) 6000 (c) 60
  11. 11.Best estimate of 22 × 36? (a) 80 (b) 800 (c) 8000
  12. 12.Best estimate of 41 × 14? (a) 4000 (b) 400 (c) 40
  13. 13.Best estimate of 78 × 80? (a) 6400 (b) 640 (c) 64000
  14. 14.Best estimate of 60 × 90? (a) 54000 (b) 5400 (c) 540
  15. 15.Best estimate of 188 + 275? (a) 500 (b) 700 (c) 300
  16. 16.Best estimate of 36 × 84? (a) 3200 (b) 320 (c) 32000
  17. 17.Best estimate of 808 + 128? (a) 900 (b) 700 (c) 1100
  18. 18.Best estimate of 71 × 61? (a) 42000 (b) 420 (c) 4200
  19. 19.Best estimate of 22 × 80? (a) 1600 (b) 16000 (c) 160
  20. 20.Best estimate of 97 × 80? (a) 800 (b) 8000 (c) 80000
  21. 21.Best estimate of 216 + 405? (a) 800 (b) 400 (c) 600
  22. 22.Best estimate of 151 + 425? (a) 800 (b) 600 (c) 400
  23. 23.Best estimate of 233 + 163? (a) 600 (b) 400 (c) 200
  24. 24.Best estimate of 637 + 792? (a) 1600 (b) 1200 (c) 1400
  25. 25.Best estimate of 21 × 38? (a) 800 (b) 80 (c) 8000
  26. 26.Best estimate of 79 × 60? (a) 48000 (b) 4800 (c) 480
  27. 27.Best estimate of 49 × 16? (a) 100 (b) 1000 (c) 10000
  28. 28.Best estimate of 19 × 58? (a) 1200 (b) 12000 (c) 120
  29. 29.Best estimate of 149 + 784? (a) 1100 (b) 900 (c) 700
  30. 30.Best estimate of 56 × 66? (a) 42000 (b) 4200 (c) 420
  31. 31.Best estimate of 40 × 69? (a) 28000 (b) 2800 (c) 280
  32. 32.Best estimate of 875 + 616? (a) 1300 (b) 1700 (c) 1500
  33. 33.Best estimate of 309 + 363? (a) 900 (b) 500 (c) 700
  34. 34.Best estimate of 73 × 42? (a) 2800 (b) 280 (c) 28000
  35. 35.Best estimate of 210 + 441? (a) 800 (b) 600 (c) 400
  36. 36.Best estimate of 67 × 66? (a) 49000 (b) 4900 (c) 490
  37. 37.Best estimate of 16 × 43? (a) 80 (b) 8000 (c) 800
  38. 38.Best estimate of 28 × 18? (a) 60 (b) 600 (c) 6000
  39. 39.Best estimate of 68 × 74? (a) 49000 (b) 4900 (c) 490
  40. 40.Best estimate of 81 × 91? (a) 720 (b) 7200 (c) 72000

Answer key

  1. 1700
  2. 1700
  3. 1700
  4. 1500
  5. 900
  6. 4000
  7. 1800
  8. 1200
  9. 300
  10. 600
  11. 800
  12. 400
  13. 6400
  14. 5400
  15. 500
  16. 3200
  17. 900
  18. 4200
  19. 1600
  20. 8000
  21. 600
  22. 600
  23. 400
  24. 1400
  25. 800
  26. 4800
  27. 1000
  28. 1200
  29. 900
  30. 4200
  31. 2800
  32. 1500
  33. 700
  34. 2800
  35. 600
  36. 4900
  37. 800
  38. 600
  39. 4900
  40. 7200

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