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Sum of 1 to 100 Worksheet

Maths tricks trick 8: Add 1 to 100 in seconds · Set 230 · 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 + 2 + 3 + … + 75 =
  2. 2.1 + 2 + 3 + … + 60 =
  3. 3.1 + 2 + 3 + … + 71 =
  4. 4.1 + 3 + 5 + … + 17 =
  5. 5.1 + 3 + 5 + … + 35 =
  6. 6.1 + 2 + 3 + … + 97 =
  7. 7.1 + 3 + 5 + … + 29 =
  8. 8.1 + 2 + 3 + … + 8 =
  9. 9.1 + 2 + 3 + … + 93 =
  10. 10.1 + 2 + 3 + … + 99 =
  11. 11.1 + 3 + 5 + … + 11 =
  12. 12.1 + 2 + 3 + … + 20 =
  13. 13.1 + 2 + 3 + … + 50 =
  14. 14.1 + 2 + 3 + … + 65 =
  15. 15.1 + 3 + 5 + … + 49 =
  16. 16.1 + 2 + 3 + … + 61 =
  17. 17.1 + 2 + 3 + … + 90 =
  18. 18.1 + 2 + 3 + … + 78 =
  19. 19.1 + 3 + 5 + … + 19 =
  20. 20.1 + 2 + 3 + … + 13 =
  21. 21.1 + 2 + 3 + … + 100 =
  22. 22.1 + 2 + 3 + … + 48 =
  23. 23.1 + 2 + 3 + … + 63 =
  24. 24.1 + 2 + 3 + … + 31 =
  25. 25.1 + 2 + 3 + … + 84 =
  26. 26.1 + 2 + 3 + … + 23 =
  27. 27.1 + 2 + 3 + … + 72 =
  28. 28.1 + 2 + 3 + … + 36 =
  29. 29.1 + 2 + 3 + … + 88 =
  30. 30.1 + 3 + 5 + … + 45 =
  31. 31.1 + 3 + 5 + … + 27 =
  32. 32.1 + 2 + 3 + … + 34 =
  33. 33.1 + 2 + 3 + … + 59 =
  34. 34.1 + 2 + 3 + … + 56 =
  35. 35.1 + 2 + 3 + … + 85 =
  36. 36.1 + 2 + 3 + … + 16 =
  37. 37.1 + 2 + 3 + … + 30 =
  38. 38.1 + 2 + 3 + … + 92 =
  39. 39.1 + 2 + 3 + … + 54 =
  40. 40.1 + 3 + 5 + … + 47 =

Answer key

  1. 2850
  2. 1830
  3. 2556
  4. 81
  5. 324
  6. 4753
  7. 225
  8. 36
  9. 4371
  10. 4950
  11. 36
  12. 210
  13. 1275
  14. 2145
  15. 625
  16. 1891
  17. 4095
  18. 3081
  19. 100
  20. 91
  21. 5050
  22. 1176
  23. 2016
  24. 496
  25. 3570
  26. 276
  27. 2628
  28. 666
  29. 3916
  30. 529
  31. 196
  32. 595
  33. 1770
  34. 1596
  35. 3655
  36. 136
  37. 465
  38. 4278
  39. 1485
  40. 576

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