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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 708 · 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 530 + 634? (a) 1300 (b) 900 (c) 1100
  2. 2.Best estimate of 151 + 215? (a) 600 (b) 400 (c) 200
  3. 3.Best estimate of 73 × 49? (a) 3500 (b) 35000 (c) 350
  4. 4.Best estimate of 488 + 763? (a) 1500 (b) 1300 (c) 1100
  5. 5.Best estimate of 56 × 50? (a) 3000 (b) 300 (c) 30000
  6. 6.Best estimate of 403 + 355? (a) 1000 (b) 800 (c) 600
  7. 7.Best estimate of 80 × 44? (a) 3200 (b) 32000 (c) 320
  8. 8.Best estimate of 29 × 59? (a) 1800 (b) 18000 (c) 180
  9. 9.Best estimate of 260 + 252? (a) 600 (b) 800 (c) 400
  10. 10.Best estimate of 648 + 256? (a) 700 (b) 900 (c) 1100
  11. 11.Best estimate of 451 + 406? (a) 700 (b) 900 (c) 1100
  12. 12.Best estimate of 720 + 227? (a) 900 (b) 1100 (c) 700
  13. 13.Best estimate of 84 × 69? (a) 560 (b) 5600 (c) 56000
  14. 14.Best estimate of 129 + 169? (a) 100 (b) 300 (c) 500
  15. 15.Best estimate of 639 + 661? (a) 1100 (b) 1300 (c) 1500
  16. 16.Best estimate of 373 + 455? (a) 700 (b) 900 (c) 1100
  17. 17.Best estimate of 787 + 685? (a) 1700 (b) 1300 (c) 1500
  18. 18.Best estimate of 577 + 155? (a) 1000 (b) 800 (c) 600
  19. 19.Best estimate of 647 + 635? (a) 1000 (b) 1400 (c) 1200
  20. 20.Best estimate of 604 + 123? (a) 700 (b) 900 (c) 500
  21. 21.Best estimate of 86 × 20? (a) 180 (b) 18000 (c) 1800
  22. 22.Best estimate of 618 + 229? (a) 1000 (b) 600 (c) 800
  23. 23.Best estimate of 69 × 93? (a) 630 (b) 63000 (c) 6300
  24. 24.Best estimate of 26 × 18? (a) 600 (b) 60 (c) 6000
  25. 25.Best estimate of 802 + 836? (a) 1600 (b) 1800 (c) 1400
  26. 26.Best estimate of 564 + 758? (a) 1400 (b) 1200 (c) 1600
  27. 27.Best estimate of 158 + 622? (a) 800 (b) 600 (c) 1000
  28. 28.Best estimate of 560 + 319? (a) 900 (b) 700 (c) 1100
  29. 29.Best estimate of 29 × 72? (a) 210 (b) 21000 (c) 2100
  30. 30.Best estimate of 174 + 188? (a) 600 (b) 400 (c) 200
  31. 31.Best estimate of 46 × 17? (a) 100 (b) 1000 (c) 10000
  32. 32.Best estimate of 32 × 72? (a) 210 (b) 2100 (c) 21000
  33. 33.Best estimate of 63 × 66? (a) 4200 (b) 42000 (c) 420
  34. 34.Best estimate of 16 × 36? (a) 800 (b) 8000 (c) 80
  35. 35.Best estimate of 27 × 23? (a) 600 (b) 60 (c) 6000
  36. 36.Best estimate of 66 × 72? (a) 490 (b) 4900 (c) 49000
  37. 37.Best estimate of 282 + 235? (a) 700 (b) 500 (c) 300
  38. 38.Best estimate of 40 × 47? (a) 20000 (b) 2000 (c) 200
  39. 39.Best estimate of 388 + 541? (a) 1100 (b) 900 (c) 700
  40. 40.Best estimate of 865 + 374? (a) 1500 (b) 1300 (c) 1100

Answer key

  1. 1100
  2. 400
  3. 3500
  4. 1300
  5. 3000
  6. 800
  7. 3200
  8. 1800
  9. 600
  10. 900
  11. 900
  12. 900
  13. 5600
  14. 300
  15. 1300
  16. 900
  17. 1500
  18. 800
  19. 1200
  20. 700
  21. 1800
  22. 800
  23. 6300
  24. 600
  25. 1600
  26. 1400
  27. 800
  28. 900
  29. 2100
  30. 400
  31. 1000
  32. 2100
  33. 4200
  34. 800
  35. 600
  36. 4900
  37. 500
  38. 2000
  39. 900
  40. 1300

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