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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 306 · 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 578 + 214? (a) 600 (b) 1000 (c) 800
  2. 2.Best estimate of 586 + 332? (a) 700 (b) 900 (c) 1100
  3. 3.Best estimate of 184 + 354? (a) 400 (b) 600 (c) 800
  4. 4.Best estimate of 398 + 809? (a) 1400 (b) 1200 (c) 1000
  5. 5.Best estimate of 662 + 217? (a) 1100 (b) 900 (c) 700
  6. 6.Best estimate of 24 × 38? (a) 800 (b) 8000 (c) 80
  7. 7.Best estimate of 207 + 608? (a) 600 (b) 1000 (c) 800
  8. 8.Best estimate of 864 + 157? (a) 1100 (b) 900 (c) 1300
  9. 9.Best estimate of 57 × 33? (a) 1800 (b) 18000 (c) 180
  10. 10.Best estimate of 56 × 19? (a) 12000 (b) 1200 (c) 120
  11. 11.Best estimate of 294 + 631? (a) 700 (b) 1100 (c) 900
  12. 12.Best estimate of 586 + 149? (a) 500 (b) 700 (c) 900
  13. 13.Best estimate of 521 + 664? (a) 1200 (b) 1400 (c) 1000
  14. 14.Best estimate of 295 + 678? (a) 800 (b) 1000 (c) 1200
  15. 15.Best estimate of 66 × 77? (a) 56000 (b) 5600 (c) 560
  16. 16.Best estimate of 86 × 48? (a) 450 (b) 45000 (c) 4500
  17. 17.Best estimate of 60 × 34? (a) 1800 (b) 18000 (c) 180
  18. 18.Best estimate of 96 × 34? (a) 3000 (b) 300 (c) 30000
  19. 19.Best estimate of 42 × 86? (a) 36000 (b) 3600 (c) 360
  20. 20.Best estimate of 577 + 347? (a) 900 (b) 700 (c) 1100
  21. 21.Best estimate of 22 × 41? (a) 8000 (b) 800 (c) 80
  22. 22.Best estimate of 314 + 202? (a) 300 (b) 700 (c) 500
  23. 23.Best estimate of 529 + 698? (a) 1200 (b) 1400 (c) 1000
  24. 24.Best estimate of 14 × 97? (a) 1000 (b) 10000 (c) 100
  25. 25.Best estimate of 81 × 61? (a) 480 (b) 48000 (c) 4800
  26. 26.Best estimate of 481 + 684? (a) 1000 (b) 1200 (c) 1400
  27. 27.Best estimate of 713 + 351? (a) 1300 (b) 1100 (c) 900
  28. 28.Best estimate of 422 + 727? (a) 1300 (b) 900 (c) 1100
  29. 29.Best estimate of 51 × 23? (a) 100 (b) 1000 (c) 10000
  30. 30.Best estimate of 76 × 53? (a) 40000 (b) 400 (c) 4000
  31. 31.Best estimate of 66 × 38? (a) 280 (b) 2800 (c) 28000
  32. 32.Best estimate of 555 + 223? (a) 800 (b) 600 (c) 1000
  33. 33.Best estimate of 24 × 33? (a) 600 (b) 6000 (c) 60
  34. 34.Best estimate of 38 × 66? (a) 2800 (b) 280 (c) 28000
  35. 35.Best estimate of 488 + 818? (a) 1500 (b) 1300 (c) 1100
  36. 36.Best estimate of 19 × 34? (a) 600 (b) 6000 (c) 60
  37. 37.Best estimate of 84 × 93? (a) 7200 (b) 72000 (c) 720
  38. 38.Best estimate of 93 × 66? (a) 63000 (b) 630 (c) 6300
  39. 39.Best estimate of 544 + 803? (a) 1500 (b) 1300 (c) 1100
  40. 40.Best estimate of 214 + 855? (a) 900 (b) 1100 (c) 1300

Answer key

  1. 800
  2. 900
  3. 600
  4. 1200
  5. 900
  6. 800
  7. 800
  8. 1100
  9. 1800
  10. 1200
  11. 900
  12. 700
  13. 1200
  14. 1000
  15. 5600
  16. 4500
  17. 1800
  18. 3000
  19. 3600
  20. 900
  21. 800
  22. 500
  23. 1200
  24. 1000
  25. 4800
  26. 1200
  27. 1100
  28. 1100
  29. 1000
  30. 4000
  31. 2800
  32. 800
  33. 600
  34. 2800
  35. 1300
  36. 600
  37. 7200
  38. 6300
  39. 1300
  40. 1100

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