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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 741 · 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 487 + 588? (a) 1100 (b) 1300 (c) 900
  2. 2.Best estimate of 32 × 49? (a) 15000 (b) 150 (c) 1500
  3. 3.Best estimate of 73 × 80? (a) 560 (b) 5600 (c) 56000
  4. 4.Best estimate of 82 × 26? (a) 240 (b) 2400 (c) 24000
  5. 5.Best estimate of 12 × 16? (a) 200 (b) 20 (c) 2000
  6. 6.Best estimate of 16 × 30? (a) 600 (b) 6000 (c) 60
  7. 7.Best estimate of 388 + 787? (a) 1400 (b) 1200 (c) 1000
  8. 8.Best estimate of 638 + 437? (a) 1200 (b) 800 (c) 1000
  9. 9.Best estimate of 770 + 224? (a) 1200 (b) 1000 (c) 800
  10. 10.Best estimate of 98 × 47? (a) 50000 (b) 5000 (c) 500
  11. 11.Best estimate of 36 × 30? (a) 120 (b) 1200 (c) 12000
  12. 12.Best estimate of 18 × 13? (a) 20 (b) 200 (c) 2000
  13. 13.Best estimate of 18 × 14? (a) 200 (b) 2000 (c) 20
  14. 14.Best estimate of 472 + 134? (a) 600 (b) 400 (c) 800
  15. 15.Best estimate of 591 + 174? (a) 800 (b) 600 (c) 1000
  16. 16.Best estimate of 309 + 145? (a) 200 (b) 600 (c) 400
  17. 17.Best estimate of 37 × 21? (a) 800 (b) 8000 (c) 80
  18. 18.Best estimate of 37 × 56? (a) 2400 (b) 240 (c) 24000
  19. 19.Best estimate of 17 × 60? (a) 12000 (b) 1200 (c) 120
  20. 20.Best estimate of 59 × 29? (a) 1800 (b) 180 (c) 18000
  21. 21.Best estimate of 63 × 66? (a) 4200 (b) 42000 (c) 420
  22. 22.Best estimate of 388 + 308? (a) 500 (b) 700 (c) 900
  23. 23.Best estimate of 220 + 236? (a) 200 (b) 400 (c) 600
  24. 24.Best estimate of 83 × 41? (a) 320 (b) 3200 (c) 32000
  25. 25.Best estimate of 57 × 51? (a) 300 (b) 3000 (c) 30000
  26. 26.Best estimate of 12 × 34? (a) 300 (b) 30 (c) 3000
  27. 27.Best estimate of 268 + 213? (a) 500 (b) 300 (c) 700
  28. 28.Best estimate of 306 + 128? (a) 400 (b) 200 (c) 600
  29. 29.Best estimate of 92 × 36? (a) 36000 (b) 360 (c) 3600
  30. 30.Best estimate of 640 + 397? (a) 800 (b) 1000 (c) 1200
  31. 31.Best estimate of 681 + 313? (a) 800 (b) 1200 (c) 1000
  32. 32.Best estimate of 185 + 316? (a) 700 (b) 300 (c) 500
  33. 33.Best estimate of 386 + 161? (a) 800 (b) 600 (c) 400
  34. 34.Best estimate of 396 + 695? (a) 1100 (b) 900 (c) 1300
  35. 35.Best estimate of 50 × 16? (a) 100 (b) 1000 (c) 10000
  36. 36.Best estimate of 651 + 313? (a) 1000 (b) 1200 (c) 800
  37. 37.Best estimate of 208 + 329? (a) 700 (b) 500 (c) 300
  38. 38.Best estimate of 22 × 43? (a) 8000 (b) 800 (c) 80
  39. 39.Best estimate of 51 × 32? (a) 1500 (b) 15000 (c) 150
  40. 40.Best estimate of 73 × 36? (a) 280 (b) 2800 (c) 28000

Answer key

  1. 1100
  2. 1500
  3. 5600
  4. 2400
  5. 200
  6. 600
  7. 1200
  8. 1000
  9. 1000
  10. 5000
  11. 1200
  12. 200
  13. 200
  14. 600
  15. 800
  16. 400
  17. 800
  18. 2400
  19. 1200
  20. 1800
  21. 4200
  22. 700
  23. 400
  24. 3200
  25. 3000
  26. 300
  27. 500
  28. 400
  29. 3600
  30. 1000
  31. 1000
  32. 500
  33. 600
  34. 1100
  35. 1000
  36. 1000
  37. 500
  38. 800
  39. 1500
  40. 2800

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