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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 171 · 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 816 + 304? (a) 900 (b) 1100 (c) 1300
  2. 2.Best estimate of 19 × 96? (a) 2000 (b) 200 (c) 20000
  3. 3.Best estimate of 30 × 13? (a) 300 (b) 30 (c) 3000
  4. 4.Best estimate of 283 + 754? (a) 1100 (b) 900 (c) 1300
  5. 5.Best estimate of 632 + 304? (a) 700 (b) 1100 (c) 900
  6. 6.Best estimate of 228 + 383? (a) 400 (b) 800 (c) 600
  7. 7.Best estimate of 38 × 34? (a) 1200 (b) 120 (c) 12000
  8. 8.Best estimate of 67 × 63? (a) 420 (b) 4200 (c) 42000
  9. 9.Best estimate of 843 + 340? (a) 1300 (b) 900 (c) 1100
  10. 10.Best estimate of 26 × 17? (a) 600 (b) 60 (c) 6000
  11. 11.Best estimate of 38 × 96? (a) 40000 (b) 4000 (c) 400
  12. 12.Best estimate of 605 + 191? (a) 600 (b) 1000 (c) 800
  13. 13.Best estimate of 760 + 627? (a) 1600 (b) 1400 (c) 1200
  14. 14.Best estimate of 52 × 36? (a) 2000 (b) 20000 (c) 200
  15. 15.Best estimate of 84 × 76? (a) 64000 (b) 6400 (c) 640
  16. 16.Best estimate of 672 + 271? (a) 1200 (b) 800 (c) 1000
  17. 17.Best estimate of 26 × 76? (a) 2400 (b) 24000 (c) 240
  18. 18.Best estimate of 531 + 438? (a) 1100 (b) 700 (c) 900
  19. 19.Best estimate of 133 + 707? (a) 1000 (b) 600 (c) 800
  20. 20.Best estimate of 16 × 44? (a) 800 (b) 80 (c) 8000
  21. 21.Best estimate of 327 + 620? (a) 700 (b) 900 (c) 1100
  22. 22.Best estimate of 351 + 279? (a) 500 (b) 900 (c) 700
  23. 23.Best estimate of 67 × 29? (a) 21000 (b) 210 (c) 2100
  24. 24.Best estimate of 807 + 296? (a) 1300 (b) 900 (c) 1100
  25. 25.Best estimate of 77 × 22? (a) 160 (b) 1600 (c) 16000
  26. 26.Best estimate of 63 × 21? (a) 120 (b) 1200 (c) 12000
  27. 27.Best estimate of 160 + 194? (a) 400 (b) 200 (c) 600
  28. 28.Best estimate of 16 × 34? (a) 60 (b) 6000 (c) 600
  29. 29.Best estimate of 86 × 82? (a) 720 (b) 7200 (c) 72000
  30. 30.Best estimate of 16 × 76? (a) 1600 (b) 160 (c) 16000
  31. 31.Best estimate of 31 × 52? (a) 150 (b) 1500 (c) 15000
  32. 32.Best estimate of 794 + 682? (a) 1700 (b) 1500 (c) 1300
  33. 33.Best estimate of 97 × 29? (a) 300 (b) 30000 (c) 3000
  34. 34.Best estimate of 73 × 36? (a) 280 (b) 28000 (c) 2800
  35. 35.Best estimate of 257 + 715? (a) 1200 (b) 1000 (c) 800
  36. 36.Best estimate of 16 × 92? (a) 18000 (b) 1800 (c) 180
  37. 37.Best estimate of 390 + 753? (a) 1000 (b) 1200 (c) 1400
  38. 38.Best estimate of 745 + 191? (a) 1100 (b) 900 (c) 700
  39. 39.Best estimate of 470 + 289? (a) 1000 (b) 600 (c) 800
  40. 40.Best estimate of 404 + 418? (a) 1000 (b) 600 (c) 800

Answer key

  1. 1100
  2. 2000
  3. 300
  4. 1100
  5. 900
  6. 600
  7. 1200
  8. 4200
  9. 1100
  10. 600
  11. 4000
  12. 800
  13. 1400
  14. 2000
  15. 6400
  16. 1000
  17. 2400
  18. 900
  19. 800
  20. 800
  21. 900
  22. 700
  23. 2100
  24. 1100
  25. 1600
  26. 1200
  27. 400
  28. 600
  29. 7200
  30. 1600
  31. 1500
  32. 1500
  33. 3000
  34. 2800
  35. 1000
  36. 1800
  37. 1200
  38. 900
  39. 800
  40. 800

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