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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 983 · 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 202 + 575? (a) 600 (b) 800 (c) 1000
  2. 2.Best estimate of 84 × 86? (a) 7200 (b) 72000 (c) 720
  3. 3.Best estimate of 51 × 83? (a) 400 (b) 40000 (c) 4000
  4. 4.Best estimate of 77 × 33? (a) 2400 (b) 24000 (c) 240
  5. 5.Best estimate of 88 × 78? (a) 72000 (b) 7200 (c) 720
  6. 6.Best estimate of 789 + 152? (a) 1000 (b) 800 (c) 1200
  7. 7.Best estimate of 421 + 185? (a) 600 (b) 800 (c) 400
  8. 8.Best estimate of 176 + 325? (a) 500 (b) 700 (c) 300
  9. 9.Best estimate of 54 × 17? (a) 10000 (b) 1000 (c) 100
  10. 10.Best estimate of 725 + 761? (a) 1500 (b) 1300 (c) 1700
  11. 11.Best estimate of 40 × 42? (a) 160 (b) 16000 (c) 1600
  12. 12.Best estimate of 66 × 60? (a) 420 (b) 42000 (c) 4200
  13. 13.Best estimate of 391 + 367? (a) 1000 (b) 800 (c) 600
  14. 14.Best estimate of 27 × 64? (a) 1800 (b) 180 (c) 18000
  15. 15.Best estimate of 24 × 56? (a) 1200 (b) 12000 (c) 120
  16. 16.Best estimate of 349 + 310? (a) 600 (b) 400 (c) 800
  17. 17.Best estimate of 70 × 47? (a) 3500 (b) 350 (c) 35000
  18. 18.Best estimate of 57 × 88? (a) 5400 (b) 540 (c) 54000
  19. 19.Best estimate of 344 + 348? (a) 800 (b) 600 (c) 400
  20. 20.Best estimate of 720 + 203? (a) 700 (b) 1100 (c) 900
  21. 21.Best estimate of 313 + 420? (a) 500 (b) 700 (c) 900
  22. 22.Best estimate of 53 × 60? (a) 3000 (b) 30000 (c) 300
  23. 23.Best estimate of 438 + 585? (a) 1000 (b) 800 (c) 1200
  24. 24.Best estimate of 470 + 360? (a) 700 (b) 900 (c) 1100
  25. 25.Best estimate of 48 × 48? (a) 25000 (b) 250 (c) 2500
  26. 26.Best estimate of 46 × 92? (a) 450 (b) 4500 (c) 45000
  27. 27.Best estimate of 121 + 529? (a) 800 (b) 400 (c) 600
  28. 28.Best estimate of 796 + 134? (a) 1100 (b) 900 (c) 700
  29. 29.Best estimate of 687 + 552? (a) 1100 (b) 1500 (c) 1300
  30. 30.Best estimate of 696 + 768? (a) 1500 (b) 1700 (c) 1300
  31. 31.Best estimate of 251 + 205? (a) 500 (b) 300 (c) 700
  32. 32.Best estimate of 43 × 59? (a) 240 (b) 24000 (c) 2400
  33. 33.Best estimate of 46 × 79? (a) 40000 (b) 4000 (c) 400
  34. 34.Best estimate of 590 + 635? (a) 1400 (b) 1000 (c) 1200
  35. 35.Best estimate of 362 + 780? (a) 1200 (b) 1000 (c) 1400
  36. 36.Best estimate of 138 + 145? (a) 0 (b) 200 (c) 400
  37. 37.Best estimate of 821 + 493? (a) 1300 (b) 1100 (c) 1500
  38. 38.Best estimate of 232 + 692? (a) 900 (b) 700 (c) 1100
  39. 39.Best estimate of 36 × 41? (a) 1600 (b) 16000 (c) 160
  40. 40.Best estimate of 845 + 670? (a) 1700 (b) 1500 (c) 1300

Answer key

  1. 800
  2. 7200
  3. 4000
  4. 2400
  5. 7200
  6. 1000
  7. 600
  8. 500
  9. 1000
  10. 1500
  11. 1600
  12. 4200
  13. 800
  14. 1800
  15. 1200
  16. 600
  17. 3500
  18. 5400
  19. 600
  20. 900
  21. 700
  22. 3000
  23. 1000
  24. 900
  25. 2500
  26. 4500
  27. 600
  28. 900
  29. 1300
  30. 1500
  31. 500
  32. 2400
  33. 4000
  34. 1200
  35. 1200
  36. 200
  37. 1300
  38. 900
  39. 1600
  40. 1500

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