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Sum of 1 to 100 Worksheet

Maths tricks trick 8: Add 1 to 100 in seconds · Set 319 · 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 + … + 36 =
  3. 3.1 + 3 + 5 + … + 41 =
  4. 4.1 + 2 + 3 + … + 73 =
  5. 5.1 + 2 + 3 + … + 81 =
  6. 6.1 + 2 + 3 + … + 91 =
  7. 7.1 + 2 + 3 + … + 26 =
  8. 8.1 + 2 + 3 + … + 98 =
  9. 9.1 + 2 + 3 + … + 8 =
  10. 10.1 + 2 + 3 + … + 18 =
  11. 11.1 + 2 + 3 + … + 80 =
  12. 12.1 + 2 + 3 + … + 21 =
  13. 13.1 + 2 + 3 + … + 23 =
  14. 14.1 + 3 + 5 + … + 43 =
  15. 15.1 + 2 + 3 + … + 28 =
  16. 16.1 + 2 + 3 + … + 47 =
  17. 17.1 + 2 + 3 + … + 85 =
  18. 18.1 + 2 + 3 + … + 50 =
  19. 19.1 + 2 + 3 + … + 84 =
  20. 20.1 + 3 + 5 + … + 39 =
  21. 21.1 + 3 + 5 + … + 31 =
  22. 22.1 + 2 + 3 + … + 66 =
  23. 23.1 + 3 + 5 + … + 35 =
  24. 24.1 + 3 + 5 + … + 13 =
  25. 25.1 + 2 + 3 + … + 13 =
  26. 26.1 + 2 + 3 + … + 92 =
  27. 27.1 + 2 + 3 + … + 11 =
  28. 28.1 + 3 + 5 + … + 37 =
  29. 29.1 + 2 + 3 + … + 22 =
  30. 30.1 + 2 + 3 + … + 32 =
  31. 31.1 + 3 + 5 + … + 11 =
  32. 32.1 + 3 + 5 + … + 25 =
  33. 33.1 + 2 + 3 + … + 71 =
  34. 34.1 + 3 + 5 + … + 17 =
  35. 35.1 + 2 + 3 + … + 77 =
  36. 36.1 + 2 + 3 + … + 74 =
  37. 37.1 + 2 + 3 + … + 20 =
  38. 38.1 + 2 + 3 + … + 46 =
  39. 39.1 + 2 + 3 + … + 9 =
  40. 40.1 + 2 + 3 + … + 93 =

Answer key

  1. 2850
  2. 666
  3. 441
  4. 2701
  5. 3321
  6. 4186
  7. 351
  8. 4851
  9. 36
  10. 171
  11. 3240
  12. 231
  13. 276
  14. 484
  15. 406
  16. 1128
  17. 3655
  18. 1275
  19. 3570
  20. 400
  21. 256
  22. 2211
  23. 324
  24. 49
  25. 91
  26. 4278
  27. 66
  28. 361
  29. 253
  30. 528
  31. 36
  32. 169
  33. 2556
  34. 81
  35. 3003
  36. 2775
  37. 210
  38. 1081
  39. 45
  40. 4371

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