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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 544 · 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 18 × 43? (a) 80 (b) 800 (c) 8000
  2. 2.Best estimate of 146 + 210? (a) 100 (b) 500 (c) 300
  3. 3.Best estimate of 81 × 83? (a) 6400 (b) 640 (c) 64000
  4. 4.Best estimate of 96 × 30? (a) 300 (b) 30000 (c) 3000
  5. 5.Best estimate of 192 + 673? (a) 700 (b) 1100 (c) 900
  6. 6.Best estimate of 157 + 366? (a) 600 (b) 800 (c) 400
  7. 7.Best estimate of 58 × 96? (a) 600 (b) 6000 (c) 60000
  8. 8.Best estimate of 34 × 46? (a) 150 (b) 1500 (c) 15000
  9. 9.Best estimate of 48 × 82? (a) 40000 (b) 400 (c) 4000
  10. 10.Best estimate of 858 + 829? (a) 1700 (b) 1900 (c) 1500
  11. 11.Best estimate of 330 + 544? (a) 600 (b) 1000 (c) 800
  12. 12.Best estimate of 27 × 13? (a) 300 (b) 30 (c) 3000
  13. 13.Best estimate of 40 × 74? (a) 28000 (b) 280 (c) 2800
  14. 14.Best estimate of 79 × 72? (a) 5600 (b) 56000 (c) 560
  15. 15.Best estimate of 406 + 343? (a) 900 (b) 700 (c) 500
  16. 16.Best estimate of 636 + 506? (a) 1300 (b) 900 (c) 1100
  17. 17.Best estimate of 36 × 67? (a) 28000 (b) 2800 (c) 280
  18. 18.Best estimate of 46 × 21? (a) 10000 (b) 1000 (c) 100
  19. 19.Best estimate of 269 + 278? (a) 600 (b) 400 (c) 800
  20. 20.Best estimate of 21 × 14? (a) 20 (b) 2000 (c) 200
  21. 21.Best estimate of 544 + 248? (a) 700 (b) 500 (c) 900
  22. 22.Best estimate of 88 × 77? (a) 720 (b) 7200 (c) 72000
  23. 23.Best estimate of 46 × 42? (a) 2000 (b) 200 (c) 20000
  24. 24.Best estimate of 97 × 47? (a) 500 (b) 5000 (c) 50000
  25. 25.Best estimate of 74 × 14? (a) 7000 (b) 700 (c) 70
  26. 26.Best estimate of 54 × 92? (a) 4500 (b) 450 (c) 45000
  27. 27.Best estimate of 403 + 380? (a) 1000 (b) 600 (c) 800
  28. 28.Best estimate of 409 + 596? (a) 1000 (b) 800 (c) 1200
  29. 29.Best estimate of 13 × 23? (a) 2000 (b) 20 (c) 200
  30. 30.Best estimate of 56 × 12? (a) 6000 (b) 60 (c) 600
  31. 31.Best estimate of 72 × 52? (a) 35000 (b) 3500 (c) 350
  32. 32.Best estimate of 50 × 91? (a) 4500 (b) 45000 (c) 450
  33. 33.Best estimate of 185 + 268? (a) 300 (b) 500 (c) 700
  34. 34.Best estimate of 241 + 211? (a) 400 (b) 600 (c) 200
  35. 35.Best estimate of 80 × 57? (a) 4800 (b) 480 (c) 48000
  36. 36.Best estimate of 382 + 716? (a) 1100 (b) 1300 (c) 900
  37. 37.Best estimate of 86 × 87? (a) 81000 (b) 810 (c) 8100
  38. 38.Best estimate of 809 + 522? (a) 1100 (b) 1300 (c) 1500
  39. 39.Best estimate of 20 × 76? (a) 1600 (b) 160 (c) 16000
  40. 40.Best estimate of 753 + 246? (a) 1200 (b) 800 (c) 1000

Answer key

  1. 800
  2. 300
  3. 6400
  4. 3000
  5. 900
  6. 600
  7. 6000
  8. 1500
  9. 4000
  10. 1700
  11. 800
  12. 300
  13. 2800
  14. 5600
  15. 700
  16. 1100
  17. 2800
  18. 1000
  19. 600
  20. 200
  21. 700
  22. 7200
  23. 2000
  24. 5000
  25. 700
  26. 4500
  27. 800
  28. 1000
  29. 200
  30. 600
  31. 3500
  32. 4500
  33. 500
  34. 400
  35. 4800
  36. 1100
  37. 8100
  38. 1300
  39. 1600
  40. 1000

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