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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 380 · 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 96 × 33? (a) 3000 (b) 300 (c) 30000
  2. 2.Best estimate of 197 + 568? (a) 800 (b) 600 (c) 1000
  3. 3.Best estimate of 97 × 59? (a) 6000 (b) 600 (c) 60000
  4. 4.Best estimate of 96 × 23? (a) 20000 (b) 200 (c) 2000
  5. 5.Best estimate of 648 + 170? (a) 800 (b) 1000 (c) 600
  6. 6.Best estimate of 807 + 253? (a) 1100 (b) 900 (c) 1300
  7. 7.Best estimate of 36 × 36? (a) 16000 (b) 1600 (c) 160
  8. 8.Best estimate of 747 + 651? (a) 1200 (b) 1400 (c) 1600
  9. 9.Best estimate of 47 × 61? (a) 30000 (b) 300 (c) 3000
  10. 10.Best estimate of 80 × 32? (a) 24000 (b) 2400 (c) 240
  11. 11.Best estimate of 93 × 82? (a) 72000 (b) 7200 (c) 720
  12. 12.Best estimate of 743 + 130? (a) 800 (b) 600 (c) 1000
  13. 13.Best estimate of 228 + 741? (a) 900 (b) 1100 (c) 700
  14. 14.Best estimate of 56 × 89? (a) 540 (b) 5400 (c) 54000
  15. 15.Best estimate of 86 × 56? (a) 54000 (b) 5400 (c) 540
  16. 16.Best estimate of 863 + 131? (a) 1200 (b) 1000 (c) 800
  17. 17.Best estimate of 70 × 37? (a) 280 (b) 2800 (c) 28000
  18. 18.Best estimate of 26 × 42? (a) 120 (b) 12000 (c) 1200
  19. 19.Best estimate of 869 + 237? (a) 900 (b) 1300 (c) 1100
  20. 20.Best estimate of 304 + 705? (a) 1000 (b) 800 (c) 1200
  21. 21.Best estimate of 723 + 177? (a) 1100 (b) 700 (c) 900
  22. 22.Best estimate of 78 × 79? (a) 640 (b) 6400 (c) 64000
  23. 23.Best estimate of 37 × 20? (a) 800 (b) 8000 (c) 80
  24. 24.Best estimate of 708 + 167? (a) 700 (b) 900 (c) 1100
  25. 25.Best estimate of 390 + 433? (a) 600 (b) 800 (c) 1000
  26. 26.Best estimate of 53 × 57? (a) 300 (b) 3000 (c) 30000
  27. 27.Best estimate of 493 + 393? (a) 700 (b) 900 (c) 1100
  28. 28.Best estimate of 692 + 446? (a) 1300 (b) 900 (c) 1100
  29. 29.Best estimate of 39 × 91? (a) 36000 (b) 360 (c) 3600
  30. 30.Best estimate of 183 + 131? (a) 100 (b) 300 (c) 500
  31. 31.Best estimate of 411 + 863? (a) 1500 (b) 1300 (c) 1100
  32. 32.Best estimate of 746 + 825? (a) 1700 (b) 1300 (c) 1500
  33. 33.Best estimate of 175 + 288? (a) 700 (b) 500 (c) 300
  34. 34.Best estimate of 41 × 38? (a) 160 (b) 16000 (c) 1600
  35. 35.Best estimate of 67 × 60? (a) 420 (b) 4200 (c) 42000
  36. 36.Best estimate of 548 + 327? (a) 600 (b) 800 (c) 1000
  37. 37.Best estimate of 86 × 68? (a) 6300 (b) 630 (c) 63000
  38. 38.Best estimate of 40 × 59? (a) 2400 (b) 240 (c) 24000
  39. 39.Best estimate of 321 + 312? (a) 400 (b) 600 (c) 800
  40. 40.Best estimate of 21 × 31? (a) 600 (b) 6000 (c) 60

Answer key

  1. 3000
  2. 800
  3. 6000
  4. 2000
  5. 800
  6. 1100
  7. 1600
  8. 1400
  9. 3000
  10. 2400
  11. 7200
  12. 800
  13. 900
  14. 5400
  15. 5400
  16. 1000
  17. 2800
  18. 1200
  19. 1100
  20. 1000
  21. 900
  22. 6400
  23. 800
  24. 900
  25. 800
  26. 3000
  27. 900
  28. 1100
  29. 3600
  30. 300
  31. 1300
  32. 1500
  33. 500
  34. 1600
  35. 4200
  36. 800
  37. 6300
  38. 2400
  39. 600
  40. 600

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