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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 41 · 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 42 × 92? (a) 3600 (b) 36000 (c) 360
  2. 2.Best estimate of 71 × 72? (a) 490 (b) 4900 (c) 49000
  3. 3.Best estimate of 430 + 151? (a) 600 (b) 400 (c) 800
  4. 4.Best estimate of 74 × 92? (a) 63000 (b) 630 (c) 6300
  5. 5.Best estimate of 80 × 96? (a) 80000 (b) 800 (c) 8000
  6. 6.Best estimate of 739 + 396? (a) 1300 (b) 900 (c) 1100
  7. 7.Best estimate of 440 + 486? (a) 900 (b) 700 (c) 1100
  8. 8.Best estimate of 326 + 133? (a) 400 (b) 200 (c) 600
  9. 9.Best estimate of 23 × 26? (a) 6000 (b) 600 (c) 60
  10. 10.Best estimate of 34 × 31? (a) 900 (b) 90 (c) 9000
  11. 11.Best estimate of 292 + 795? (a) 900 (b) 1300 (c) 1100
  12. 12.Best estimate of 211 + 684? (a) 700 (b) 900 (c) 1100
  13. 13.Best estimate of 469 + 370? (a) 700 (b) 900 (c) 1100
  14. 14.Best estimate of 87 × 34? (a) 2700 (b) 270 (c) 27000
  15. 15.Best estimate of 67 × 54? (a) 3500 (b) 35000 (c) 350
  16. 16.Best estimate of 278 + 436? (a) 700 (b) 900 (c) 500
  17. 17.Best estimate of 398 + 288? (a) 700 (b) 500 (c) 900
  18. 18.Best estimate of 21 × 23? (a) 4000 (b) 400 (c) 40
  19. 19.Best estimate of 300 + 448? (a) 500 (b) 700 (c) 900
  20. 20.Best estimate of 16 × 57? (a) 1200 (b) 120 (c) 12000
  21. 21.Best estimate of 47 × 97? (a) 50000 (b) 500 (c) 5000
  22. 22.Best estimate of 16 × 52? (a) 10000 (b) 1000 (c) 100
  23. 23.Best estimate of 14 × 94? (a) 90 (b) 900 (c) 9000
  24. 24.Best estimate of 804 + 657? (a) 1700 (b) 1500 (c) 1300
  25. 25.Best estimate of 22 × 64? (a) 120 (b) 1200 (c) 12000
  26. 26.Best estimate of 292 + 197? (a) 500 (b) 300 (c) 700
  27. 27.Best estimate of 520 + 815? (a) 1300 (b) 1500 (c) 1100
  28. 28.Best estimate of 610 + 142? (a) 900 (b) 500 (c) 700
  29. 29.Best estimate of 64 × 96? (a) 600 (b) 60000 (c) 6000
  30. 30.Best estimate of 41 × 70? (a) 2800 (b) 280 (c) 28000
  31. 31.Best estimate of 486 + 509? (a) 800 (b) 1200 (c) 1000
  32. 32.Best estimate of 189 + 462? (a) 700 (b) 900 (c) 500
  33. 33.Best estimate of 158 + 789? (a) 800 (b) 1000 (c) 1200
  34. 34.Best estimate of 313 + 532? (a) 1000 (b) 800 (c) 600
  35. 35.Best estimate of 87 × 88? (a) 8100 (b) 810 (c) 81000
  36. 36.Best estimate of 83 × 80? (a) 640 (b) 64000 (c) 6400
  37. 37.Best estimate of 204 + 541? (a) 700 (b) 900 (c) 500
  38. 38.Best estimate of 243 + 538? (a) 900 (b) 500 (c) 700
  39. 39.Best estimate of 775 + 861? (a) 1700 (b) 1900 (c) 1500
  40. 40.Best estimate of 281 + 810? (a) 1300 (b) 900 (c) 1100

Answer key

  1. 3600
  2. 4900
  3. 600
  4. 6300
  5. 8000
  6. 1100
  7. 900
  8. 400
  9. 600
  10. 900
  11. 1100
  12. 900
  13. 900
  14. 2700
  15. 3500
  16. 700
  17. 700
  18. 400
  19. 700
  20. 1200
  21. 5000
  22. 1000
  23. 900
  24. 1500
  25. 1200
  26. 500
  27. 1300
  28. 700
  29. 6000
  30. 2800
  31. 1000
  32. 700
  33. 1000
  34. 800
  35. 8100
  36. 6400
  37. 700
  38. 700
  39. 1700
  40. 1100

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