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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 268 · 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 12 × 29? (a) 30 (b) 3000 (c) 300
  2. 2.Best estimate of 164 + 444? (a) 600 (b) 400 (c) 800
  3. 3.Best estimate of 409 + 367? (a) 800 (b) 600 (c) 1000
  4. 4.Best estimate of 86 × 96? (a) 90000 (b) 9000 (c) 900
  5. 5.Best estimate of 148 + 205? (a) 100 (b) 500 (c) 300
  6. 6.Best estimate of 16 × 57? (a) 120 (b) 12000 (c) 1200
  7. 7.Best estimate of 819 + 284? (a) 1100 (b) 900 (c) 1300
  8. 8.Best estimate of 33 × 17? (a) 6000 (b) 60 (c) 600
  9. 9.Best estimate of 91 × 47? (a) 450 (b) 4500 (c) 45000
  10. 10.Best estimate of 60 × 82? (a) 480 (b) 48000 (c) 4800
  11. 11.Best estimate of 81 × 86? (a) 72000 (b) 720 (c) 7200
  12. 12.Best estimate of 495 + 180? (a) 700 (b) 500 (c) 900
  13. 13.Best estimate of 90 × 14? (a) 9000 (b) 90 (c) 900
  14. 14.Best estimate of 633 + 844? (a) 1600 (b) 1400 (c) 1200
  15. 15.Best estimate of 357 + 860? (a) 1300 (b) 1500 (c) 1100
  16. 16.Best estimate of 12 × 53? (a) 5000 (b) 50 (c) 500
  17. 17.Best estimate of 351 + 407? (a) 600 (b) 1000 (c) 800
  18. 18.Best estimate of 326 + 434? (a) 900 (b) 700 (c) 500
  19. 19.Best estimate of 68 × 78? (a) 560 (b) 56000 (c) 5600
  20. 20.Best estimate of 51 × 20? (a) 1000 (b) 10000 (c) 100
  21. 21.Best estimate of 13 × 79? (a) 800 (b) 8000 (c) 80
  22. 22.Best estimate of 38 × 71? (a) 2800 (b) 280 (c) 28000
  23. 23.Best estimate of 393 + 281? (a) 900 (b) 500 (c) 700
  24. 24.Best estimate of 777 + 540? (a) 1500 (b) 1100 (c) 1300
  25. 25.Best estimate of 248 + 135? (a) 100 (b) 500 (c) 300
  26. 26.Best estimate of 238 + 805? (a) 800 (b) 1200 (c) 1000
  27. 27.Best estimate of 211 + 280? (a) 300 (b) 700 (c) 500
  28. 28.Best estimate of 409 + 355? (a) 600 (b) 800 (c) 1000
  29. 29.Best estimate of 29 × 74? (a) 210 (b) 2100 (c) 21000
  30. 30.Best estimate of 27 × 13? (a) 30 (b) 3000 (c) 300
  31. 31.Best estimate of 79 × 94? (a) 720 (b) 7200 (c) 72000
  32. 32.Best estimate of 200 + 682? (a) 1100 (b) 700 (c) 900
  33. 33.Best estimate of 89 × 70? (a) 630 (b) 6300 (c) 63000
  34. 34.Best estimate of 89 × 66? (a) 6300 (b) 63000 (c) 630
  35. 35.Best estimate of 27 × 62? (a) 18000 (b) 180 (c) 1800
  36. 36.Best estimate of 66 × 29? (a) 210 (b) 21000 (c) 2100
  37. 37.Best estimate of 26 × 18? (a) 6000 (b) 600 (c) 60
  38. 38.Best estimate of 90 × 19? (a) 1800 (b) 180 (c) 18000
  39. 39.Best estimate of 299 + 146? (a) 600 (b) 200 (c) 400
  40. 40.Best estimate of 12 × 62? (a) 600 (b) 6000 (c) 60

Answer key

  1. 300
  2. 600
  3. 800
  4. 9000
  5. 300
  6. 1200
  7. 1100
  8. 600
  9. 4500
  10. 4800
  11. 7200
  12. 700
  13. 900
  14. 1400
  15. 1300
  16. 500
  17. 800
  18. 700
  19. 5600
  20. 1000
  21. 800
  22. 2800
  23. 700
  24. 1300
  25. 300
  26. 1000
  27. 500
  28. 800
  29. 2100
  30. 300
  31. 7200
  32. 900
  33. 6300
  34. 6300
  35. 1800
  36. 2100
  37. 600
  38. 1800
  39. 400
  40. 600

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