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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 227 · 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 359 + 264? (a) 700 (b) 500 (c) 900
  2. 2.Best estimate of 487 + 564? (a) 1300 (b) 900 (c) 1100
  3. 3.Best estimate of 54 × 20? (a) 1000 (b) 10000 (c) 100
  4. 4.Best estimate of 506 + 163? (a) 700 (b) 900 (c) 500
  5. 5.Best estimate of 385 + 623? (a) 800 (b) 1200 (c) 1000
  6. 6.Best estimate of 147 + 422? (a) 700 (b) 300 (c) 500
  7. 7.Best estimate of 98 × 29? (a) 30000 (b) 300 (c) 3000
  8. 8.Best estimate of 821 + 352? (a) 1000 (b) 1200 (c) 1400
  9. 9.Best estimate of 73 × 92? (a) 6300 (b) 63000 (c) 630
  10. 10.Best estimate of 713 + 141? (a) 800 (b) 600 (c) 1000
  11. 11.Best estimate of 49 × 40? (a) 20000 (b) 2000 (c) 200
  12. 12.Best estimate of 52 × 33? (a) 150 (b) 1500 (c) 15000
  13. 13.Best estimate of 562 + 716? (a) 1500 (b) 1300 (c) 1100
  14. 14.Best estimate of 66 × 79? (a) 560 (b) 5600 (c) 56000
  15. 15.Best estimate of 751 + 637? (a) 1600 (b) 1400 (c) 1200
  16. 16.Best estimate of 80 × 39? (a) 3200 (b) 32000 (c) 320
  17. 17.Best estimate of 80 × 12? (a) 80 (b) 800 (c) 8000
  18. 18.Best estimate of 818 + 128? (a) 700 (b) 1100 (c) 900
  19. 19.Best estimate of 83 × 36? (a) 320 (b) 3200 (c) 32000
  20. 20.Best estimate of 37 × 19? (a) 80 (b) 800 (c) 8000
  21. 21.Best estimate of 634 + 807? (a) 1200 (b) 1600 (c) 1400
  22. 22.Best estimate of 31 × 38? (a) 12000 (b) 1200 (c) 120
  23. 23.Best estimate of 68 × 83? (a) 560 (b) 56000 (c) 5600
  24. 24.Best estimate of 261 + 128? (a) 600 (b) 200 (c) 400
  25. 25.Best estimate of 69 × 63? (a) 4200 (b) 42000 (c) 420
  26. 26.Best estimate of 93 × 21? (a) 180 (b) 1800 (c) 18000
  27. 27.Best estimate of 84 × 70? (a) 5600 (b) 560 (c) 56000
  28. 28.Best estimate of 805 + 172? (a) 1200 (b) 800 (c) 1000
  29. 29.Best estimate of 12 × 21? (a) 200 (b) 20 (c) 2000
  30. 30.Best estimate of 127 + 334? (a) 600 (b) 200 (c) 400
  31. 31.Best estimate of 51 × 33? (a) 15000 (b) 1500 (c) 150
  32. 32.Best estimate of 22 × 51? (a) 100 (b) 1000 (c) 10000
  33. 33.Best estimate of 72 × 88? (a) 630 (b) 6300 (c) 63000
  34. 34.Best estimate of 412 + 371? (a) 1000 (b) 800 (c) 600
  35. 35.Best estimate of 32 × 69? (a) 21000 (b) 2100 (c) 210
  36. 36.Best estimate of 28 × 72? (a) 21000 (b) 2100 (c) 210
  37. 37.Best estimate of 57 × 60? (a) 3600 (b) 36000 (c) 360
  38. 38.Best estimate of 46 × 98? (a) 500 (b) 5000 (c) 50000
  39. 39.Best estimate of 26 × 86? (a) 2700 (b) 270 (c) 27000
  40. 40.Best estimate of 696 + 814? (a) 1500 (b) 1700 (c) 1300

Answer key

  1. 700
  2. 1100
  3. 1000
  4. 700
  5. 1000
  6. 500
  7. 3000
  8. 1200
  9. 6300
  10. 800
  11. 2000
  12. 1500
  13. 1300
  14. 5600
  15. 1400
  16. 3200
  17. 800
  18. 900
  19. 3200
  20. 800
  21. 1400
  22. 1200
  23. 5600
  24. 400
  25. 4200
  26. 1800
  27. 5600
  28. 1000
  29. 200
  30. 400
  31. 1500
  32. 1000
  33. 6300
  34. 800
  35. 2100
  36. 2100
  37. 3600
  38. 5000
  39. 2700
  40. 1500

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