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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 30 · 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 342 + 581? (a) 900 (b) 1100 (c) 700
  2. 2.Best estimate of 36 × 60? (a) 2400 (b) 24000 (c) 240
  3. 3.Best estimate of 37 × 27? (a) 12000 (b) 120 (c) 1200
  4. 4.Best estimate of 182 + 279? (a) 700 (b) 300 (c) 500
  5. 5.Best estimate of 244 + 601? (a) 1000 (b) 800 (c) 600
  6. 6.Best estimate of 446 + 378? (a) 1000 (b) 800 (c) 600
  7. 7.Best estimate of 636 + 877? (a) 1300 (b) 1500 (c) 1700
  8. 8.Best estimate of 282 + 828? (a) 1300 (b) 1100 (c) 900
  9. 9.Best estimate of 179 + 715? (a) 1100 (b) 900 (c) 700
  10. 10.Best estimate of 96 × 89? (a) 900 (b) 90000 (c) 9000
  11. 11.Best estimate of 254 + 676? (a) 1000 (b) 800 (c) 1200
  12. 12.Best estimate of 626 + 734? (a) 1100 (b) 1300 (c) 1500
  13. 13.Best estimate of 86 × 13? (a) 900 (b) 9000 (c) 90
  14. 14.Best estimate of 54 × 68? (a) 350 (b) 3500 (c) 35000
  15. 15.Best estimate of 454 + 277? (a) 600 (b) 1000 (c) 800
  16. 16.Best estimate of 244 + 517? (a) 900 (b) 700 (c) 500
  17. 17.Best estimate of 479 + 651? (a) 1200 (b) 1000 (c) 1400
  18. 18.Best estimate of 211 + 230? (a) 200 (b) 400 (c) 600
  19. 19.Best estimate of 97 × 12? (a) 100 (b) 1000 (c) 10000
  20. 20.Best estimate of 783 + 193? (a) 1000 (b) 1200 (c) 800
  21. 21.Best estimate of 86 × 31? (a) 27000 (b) 2700 (c) 270
  22. 22.Best estimate of 39 × 96? (a) 400 (b) 40000 (c) 4000
  23. 23.Best estimate of 20 × 44? (a) 800 (b) 8000 (c) 80
  24. 24.Best estimate of 71 × 87? (a) 6300 (b) 63000 (c) 630
  25. 25.Best estimate of 868 + 323? (a) 1200 (b) 1400 (c) 1000
  26. 26.Best estimate of 37 × 96? (a) 4000 (b) 40000 (c) 400
  27. 27.Best estimate of 783 + 266? (a) 1100 (b) 900 (c) 1300
  28. 28.Best estimate of 44 × 58? (a) 2400 (b) 24000 (c) 240
  29. 29.Best estimate of 92 × 13? (a) 900 (b) 9000 (c) 90
  30. 30.Best estimate of 71 × 16? (a) 1400 (b) 14000 (c) 140
  31. 31.Best estimate of 568 + 693? (a) 1500 (b) 1300 (c) 1100
  32. 32.Best estimate of 24 × 80? (a) 1600 (b) 160 (c) 16000
  33. 33.Best estimate of 225 + 555? (a) 1000 (b) 800 (c) 600
  34. 34.Best estimate of 79 × 38? (a) 320 (b) 32000 (c) 3200
  35. 35.Best estimate of 59 × 96? (a) 6000 (b) 600 (c) 60000
  36. 36.Best estimate of 41 × 29? (a) 12000 (b) 1200 (c) 120
  37. 37.Best estimate of 43 × 30? (a) 120 (b) 1200 (c) 12000
  38. 38.Best estimate of 20 × 36? (a) 8000 (b) 80 (c) 800
  39. 39.Best estimate of 58 × 84? (a) 48000 (b) 480 (c) 4800
  40. 40.Best estimate of 16 × 68? (a) 1400 (b) 14000 (c) 140

Answer key

  1. 900
  2. 2400
  3. 1200
  4. 500
  5. 800
  6. 800
  7. 1500
  8. 1100
  9. 900
  10. 9000
  11. 1000
  12. 1300
  13. 900
  14. 3500
  15. 800
  16. 700
  17. 1200
  18. 400
  19. 1000
  20. 1000
  21. 2700
  22. 4000
  23. 800
  24. 6300
  25. 1200
  26. 4000
  27. 1100
  28. 2400
  29. 900
  30. 1400
  31. 1300
  32. 1600
  33. 800
  34. 3200
  35. 6000
  36. 1200
  37. 1200
  38. 800
  39. 4800
  40. 1400

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