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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 561 · 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 53 × 26? (a) 1500 (b) 15000 (c) 150
  2. 2.Best estimate of 125 + 288? (a) 400 (b) 600 (c) 200
  3. 3.Best estimate of 486 + 347? (a) 800 (b) 600 (c) 1000
  4. 4.Best estimate of 49 × 37? (a) 20000 (b) 2000 (c) 200
  5. 5.Best estimate of 779 + 420? (a) 1200 (b) 1400 (c) 1000
  6. 6.Best estimate of 66 × 30? (a) 210 (b) 2100 (c) 21000
  7. 7.Best estimate of 184 + 314? (a) 500 (b) 700 (c) 300
  8. 8.Best estimate of 38 × 77? (a) 320 (b) 3200 (c) 32000
  9. 9.Best estimate of 868 + 777? (a) 1700 (b) 1900 (c) 1500
  10. 10.Best estimate of 678 + 228? (a) 700 (b) 900 (c) 1100
  11. 11.Best estimate of 642 + 631? (a) 1200 (b) 1400 (c) 1000
  12. 12.Best estimate of 72 × 47? (a) 350 (b) 3500 (c) 35000
  13. 13.Best estimate of 444 + 597? (a) 1200 (b) 800 (c) 1000
  14. 14.Best estimate of 59 × 24? (a) 120 (b) 1200 (c) 12000
  15. 15.Best estimate of 40 × 68? (a) 280 (b) 2800 (c) 28000
  16. 16.Best estimate of 422 + 733? (a) 1300 (b) 900 (c) 1100
  17. 17.Best estimate of 255 + 729? (a) 1000 (b) 800 (c) 1200
  18. 18.Best estimate of 87 × 97? (a) 9000 (b) 90000 (c) 900
  19. 19.Best estimate of 240 + 827? (a) 1000 (b) 800 (c) 1200
  20. 20.Best estimate of 18 × 72? (a) 1400 (b) 14000 (c) 140
  21. 21.Best estimate of 22 × 87? (a) 1800 (b) 180 (c) 18000
  22. 22.Best estimate of 544 + 341? (a) 1000 (b) 800 (c) 600
  23. 23.Best estimate of 62 × 43? (a) 2400 (b) 240 (c) 24000
  24. 24.Best estimate of 26 × 76? (a) 24000 (b) 240 (c) 2400
  25. 25.Best estimate of 390 + 571? (a) 1200 (b) 1000 (c) 800
  26. 26.Best estimate of 27 × 19? (a) 600 (b) 60 (c) 6000
  27. 27.Best estimate of 749 + 527? (a) 1200 (b) 1400 (c) 1000
  28. 28.Best estimate of 260 + 762? (a) 900 (b) 1100 (c) 1300
  29. 29.Best estimate of 129 + 392? (a) 700 (b) 300 (c) 500
  30. 30.Best estimate of 50 × 30? (a) 15000 (b) 150 (c) 1500
  31. 31.Best estimate of 211 + 526? (a) 500 (b) 700 (c) 900
  32. 32.Best estimate of 96 × 26? (a) 300 (b) 30000 (c) 3000
  33. 33.Best estimate of 43 × 24? (a) 8000 (b) 80 (c) 800
  34. 34.Best estimate of 96 × 82? (a) 80000 (b) 800 (c) 8000
  35. 35.Best estimate of 608 + 423? (a) 1000 (b) 1200 (c) 800
  36. 36.Best estimate of 66 × 43? (a) 2800 (b) 280 (c) 28000
  37. 37.Best estimate of 551 + 289? (a) 700 (b) 900 (c) 1100
  38. 38.Best estimate of 791 + 231? (a) 1000 (b) 800 (c) 1200
  39. 39.Best estimate of 23 × 93? (a) 18000 (b) 180 (c) 1800
  40. 40.Best estimate of 56 × 49? (a) 3000 (b) 300 (c) 30000

Answer key

  1. 1500
  2. 400
  3. 800
  4. 2000
  5. 1200
  6. 2100
  7. 500
  8. 3200
  9. 1700
  10. 900
  11. 1200
  12. 3500
  13. 1000
  14. 1200
  15. 2800
  16. 1100
  17. 1000
  18. 9000
  19. 1000
  20. 1400
  21. 1800
  22. 800
  23. 2400
  24. 2400
  25. 1000
  26. 600
  27. 1200
  28. 1100
  29. 500
  30. 1500
  31. 700
  32. 3000
  33. 800
  34. 8000
  35. 1000
  36. 2800
  37. 900
  38. 1000
  39. 1800
  40. 3000

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