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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 510 · 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 710 + 828? (a) 1500 (b) 1300 (c) 1700
  2. 2.Best estimate of 40 × 46? (a) 20000 (b) 200 (c) 2000
  3. 3.Best estimate of 59 × 23? (a) 1200 (b) 12000 (c) 120
  4. 4.Best estimate of 830 + 700? (a) 1700 (b) 1300 (c) 1500
  5. 5.Best estimate of 649 + 801? (a) 1600 (b) 1400 (c) 1200
  6. 6.Best estimate of 321 + 578? (a) 900 (b) 1100 (c) 700
  7. 7.Best estimate of 684 + 231? (a) 1100 (b) 900 (c) 700
  8. 8.Best estimate of 313 + 666? (a) 1200 (b) 1000 (c) 800
  9. 9.Best estimate of 856 + 146? (a) 1000 (b) 1200 (c) 800
  10. 10.Best estimate of 795 + 483? (a) 1500 (b) 1300 (c) 1100
  11. 11.Best estimate of 70 × 46? (a) 35000 (b) 350 (c) 3500
  12. 12.Best estimate of 98 × 94? (a) 900 (b) 90000 (c) 9000
  13. 13.Best estimate of 56 × 30? (a) 180 (b) 1800 (c) 18000
  14. 14.Best estimate of 261 + 863? (a) 1400 (b) 1200 (c) 1000
  15. 15.Best estimate of 67 × 59? (a) 42000 (b) 420 (c) 4200
  16. 16.Best estimate of 269 + 293? (a) 800 (b) 600 (c) 400
  17. 17.Best estimate of 479 + 329? (a) 1000 (b) 600 (c) 800
  18. 18.Best estimate of 264 + 508? (a) 1000 (b) 800 (c) 600
  19. 19.Best estimate of 51 × 96? (a) 500 (b) 50000 (c) 5000
  20. 20.Best estimate of 12 × 96? (a) 100 (b) 1000 (c) 10000
  21. 21.Best estimate of 90 × 19? (a) 1800 (b) 180 (c) 18000
  22. 22.Best estimate of 71 × 79? (a) 56000 (b) 560 (c) 5600
  23. 23.Best estimate of 228 + 301? (a) 700 (b) 300 (c) 500
  24. 24.Best estimate of 533 + 327? (a) 600 (b) 800 (c) 1000
  25. 25.Best estimate of 354 + 174? (a) 400 (b) 800 (c) 600
  26. 26.Best estimate of 720 + 216? (a) 900 (b) 1100 (c) 700
  27. 27.Best estimate of 23 × 86? (a) 180 (b) 1800 (c) 18000
  28. 28.Best estimate of 19 × 96? (a) 2000 (b) 200 (c) 20000
  29. 29.Best estimate of 554 + 587? (a) 1200 (b) 1400 (c) 1000
  30. 30.Best estimate of 722 + 132? (a) 1000 (b) 800 (c) 600
  31. 31.Best estimate of 509 + 218? (a) 500 (b) 900 (c) 700
  32. 32.Best estimate of 260 + 867? (a) 1400 (b) 1200 (c) 1000
  33. 33.Best estimate of 67 × 23? (a) 1400 (b) 140 (c) 14000
  34. 34.Best estimate of 401 + 276? (a) 900 (b) 700 (c) 500
  35. 35.Best estimate of 834 + 536? (a) 1500 (b) 1300 (c) 1100
  36. 36.Best estimate of 44 × 97? (a) 40000 (b) 400 (c) 4000
  37. 37.Best estimate of 89 × 47? (a) 45000 (b) 450 (c) 4500
  38. 38.Best estimate of 344 + 704? (a) 1000 (b) 800 (c) 1200
  39. 39.Best estimate of 249 + 221? (a) 600 (b) 200 (c) 400
  40. 40.Best estimate of 747 + 204? (a) 900 (b) 700 (c) 1100

Answer key

  1. 1500
  2. 2000
  3. 1200
  4. 1500
  5. 1400
  6. 900
  7. 900
  8. 1000
  9. 1000
  10. 1300
  11. 3500
  12. 9000
  13. 1800
  14. 1200
  15. 4200
  16. 600
  17. 800
  18. 800
  19. 5000
  20. 1000
  21. 1800
  22. 5600
  23. 500
  24. 800
  25. 600
  26. 900
  27. 1800
  28. 2000
  29. 1200
  30. 800
  31. 700
  32. 1200
  33. 1400
  34. 700
  35. 1300
  36. 4000
  37. 4500
  38. 1000
  39. 400
  40. 900

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