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Sum of 1 to 100 Worksheet

Maths tricks trick 8: Add 1 to 100 in seconds · Set 822 · 40 questions
TalentJR

The trick (Pairs): Pair the first and last numbers: each pair adds to n + 1. Count the pairs — or multiply n × (n + 1) and halve it. Odd numbers 1 + 3 + 5 + …: count them and multiply that count by itself.

NameDateTime takenScore ___ / 40
  1. 1.1 + 3 + 5 + … + 19 =
  2. 2.1 + 2 + 3 + … + 99 =
  3. 3.1 + 2 + 3 + … + 98 =
  4. 4.1 + 2 + 3 + … + 18 =
  5. 5.1 + 2 + 3 + … + 60 =
  6. 6.1 + 2 + 3 + … + 10 =
  7. 7.1 + 2 + 3 + … + 58 =
  8. 8.1 + 2 + 3 + … + 91 =
  9. 9.1 + 3 + 5 + … + 47 =
  10. 10.1 + 2 + 3 + … + 37 =
  11. 11.1 + 2 + 3 + … + 83 =
  12. 12.1 + 2 + 3 + … + 75 =
  13. 13.1 + 2 + 3 + … + 23 =
  14. 14.1 + 2 + 3 + … + 12 =
  15. 15.1 + 2 + 3 + … + 68 =
  16. 16.1 + 3 + 5 + … + 23 =
  17. 17.1 + 2 + 3 + … + 74 =
  18. 18.1 + 3 + 5 + … + 25 =
  19. 19.1 + 3 + 5 + … + 35 =
  20. 20.1 + 3 + 5 + … + 31 =
  21. 21.1 + 2 + 3 + … + 67 =
  22. 22.1 + 2 + 3 + … + 84 =
  23. 23.1 + 2 + 3 + … + 38 =
  24. 24.1 + 2 + 3 + … + 90 =
  25. 25.1 + 2 + 3 + … + 34 =
  26. 26.1 + 2 + 3 + … + 19 =
  27. 27.1 + 2 + 3 + … + 61 =
  28. 28.1 + 3 + 5 + … + 13 =
  29. 29.1 + 3 + 5 + … + 15 =
  30. 30.1 + 2 + 3 + … + 36 =
  31. 31.1 + 2 + 3 + … + 13 =
  32. 32.1 + 3 + 5 + … + 49 =
  33. 33.1 + 2 + 3 + … + 41 =
  34. 34.1 + 2 + 3 + … + 79 =
  35. 35.1 + 2 + 3 + … + 80 =
  36. 36.1 + 2 + 3 + … + 100 =
  37. 37.1 + 2 + 3 + … + 69 =
  38. 38.1 + 2 + 3 + … + 52 =
  39. 39.1 + 2 + 3 + … + 76 =
  40. 40.1 + 2 + 3 + … + 11 =

Answer key

  1. 100
  2. 4950
  3. 4851
  4. 171
  5. 1830
  6. 55
  7. 1711
  8. 4186
  9. 576
  10. 703
  11. 3486
  12. 2850
  13. 276
  14. 78
  15. 2346
  16. 144
  17. 2775
  18. 169
  19. 324
  20. 256
  21. 2278
  22. 3570
  23. 741
  24. 4095
  25. 595
  26. 190
  27. 1891
  28. 49
  29. 64
  30. 666
  31. 91
  32. 625
  33. 861
  34. 3160
  35. 3240
  36. 5050
  37. 2415
  38. 1378
  39. 2926
  40. 66

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