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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 263 · 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 241 + 127? (a) 100 (b) 500 (c) 300
  2. 2.Best estimate of 14 × 50? (a) 5000 (b) 500 (c) 50
  3. 3.Best estimate of 73 × 97? (a) 700 (b) 7000 (c) 70000
  4. 4.Best estimate of 181 + 573? (a) 600 (b) 800 (c) 1000
  5. 5.Best estimate of 493 + 426? (a) 900 (b) 700 (c) 1100
  6. 6.Best estimate of 53 × 28? (a) 15000 (b) 1500 (c) 150
  7. 7.Best estimate of 366 + 551? (a) 1200 (b) 1000 (c) 800
  8. 8.Best estimate of 84 × 89? (a) 72000 (b) 720 (c) 7200
  9. 9.Best estimate of 89 × 36? (a) 360 (b) 3600 (c) 36000
  10. 10.Best estimate of 251 + 325? (a) 600 (b) 800 (c) 400
  11. 11.Best estimate of 68 × 98? (a) 70000 (b) 700 (c) 7000
  12. 12.Best estimate of 584 + 819? (a) 1400 (b) 1200 (c) 1600
  13. 13.Best estimate of 317 + 388? (a) 500 (b) 900 (c) 700
  14. 14.Best estimate of 558 + 213? (a) 800 (b) 600 (c) 1000
  15. 15.Best estimate of 56 × 33? (a) 1800 (b) 18000 (c) 180
  16. 16.Best estimate of 204 + 210? (a) 400 (b) 600 (c) 200
  17. 17.Best estimate of 19 × 17? (a) 40 (b) 4000 (c) 400
  18. 18.Best estimate of 49 × 78? (a) 400 (b) 40000 (c) 4000
  19. 19.Best estimate of 233 + 542? (a) 900 (b) 500 (c) 700
  20. 20.Best estimate of 555 + 760? (a) 1400 (b) 1600 (c) 1200
  21. 21.Best estimate of 52 × 54? (a) 2500 (b) 250 (c) 25000
  22. 22.Best estimate of 143 + 304? (a) 600 (b) 200 (c) 400
  23. 23.Best estimate of 259 + 158? (a) 500 (b) 300 (c) 700
  24. 24.Best estimate of 54 × 31? (a) 15000 (b) 1500 (c) 150
  25. 25.Best estimate of 786 + 728? (a) 1700 (b) 1500 (c) 1300
  26. 26.Best estimate of 492 + 604? (a) 900 (b) 1300 (c) 1100
  27. 27.Best estimate of 540 + 175? (a) 500 (b) 700 (c) 900
  28. 28.Best estimate of 531 + 356? (a) 1100 (b) 900 (c) 700
  29. 29.Best estimate of 644 + 709? (a) 1300 (b) 1100 (c) 1500
  30. 30.Best estimate of 445 + 244? (a) 800 (b) 400 (c) 600
  31. 31.Best estimate of 12 × 71? (a) 700 (b) 70 (c) 7000
  32. 32.Best estimate of 205 + 135? (a) 500 (b) 300 (c) 100
  33. 33.Best estimate of 70 × 37? (a) 28000 (b) 280 (c) 2800
  34. 34.Best estimate of 53 × 72? (a) 35000 (b) 3500 (c) 350
  35. 35.Best estimate of 500 + 321? (a) 1000 (b) 600 (c) 800
  36. 36.Best estimate of 21 × 13? (a) 2000 (b) 20 (c) 200
  37. 37.Best estimate of 98 × 32? (a) 300 (b) 3000 (c) 30000
  38. 38.Best estimate of 802 + 507? (a) 1300 (b) 1100 (c) 1500
  39. 39.Best estimate of 641 + 879? (a) 1700 (b) 1500 (c) 1300
  40. 40.Best estimate of 229 + 445? (a) 800 (b) 400 (c) 600

Answer key

  1. 300
  2. 500
  3. 7000
  4. 800
  5. 900
  6. 1500
  7. 1000
  8. 7200
  9. 3600
  10. 600
  11. 7000
  12. 1400
  13. 700
  14. 800
  15. 1800
  16. 400
  17. 400
  18. 4000
  19. 700
  20. 1400
  21. 2500
  22. 400
  23. 500
  24. 1500
  25. 1500
  26. 1100
  27. 700
  28. 900
  29. 1300
  30. 600
  31. 700
  32. 300
  33. 2800
  34. 3500
  35. 800
  36. 200
  37. 3000
  38. 1300
  39. 1500
  40. 600

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