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Sum of 1 to 100 Worksheet

Maths tricks trick 8: Add 1 to 100 in seconds · Set 475 · 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 + … + 8 =
  2. 2.1 + 2 + 3 + … + 94 =
  3. 3.1 + 2 + 3 + … + 85 =
  4. 4.1 + 2 + 3 + … + 10 =
  5. 5.1 + 2 + 3 + … + 100 =
  6. 6.1 + 2 + 3 + … + 84 =
  7. 7.1 + 2 + 3 + … + 27 =
  8. 8.1 + 3 + 5 + … + 9 =
  9. 9.1 + 2 + 3 + … + 72 =
  10. 10.1 + 2 + 3 + … + 24 =
  11. 11.1 + 2 + 3 + … + 90 =
  12. 12.1 + 2 + 3 + … + 92 =
  13. 13.1 + 3 + 5 + … + 19 =
  14. 14.1 + 3 + 5 + … + 15 =
  15. 15.1 + 2 + 3 + … + 51 =
  16. 16.1 + 2 + 3 + … + 93 =
  17. 17.1 + 3 + 5 + … + 29 =
  18. 18.1 + 2 + 3 + … + 95 =
  19. 19.1 + 2 + 3 + … + 43 =
  20. 20.1 + 2 + 3 + … + 76 =
  21. 21.1 + 3 + 5 + … + 13 =
  22. 22.1 + 2 + 3 + … + 12 =
  23. 23.1 + 2 + 3 + … + 78 =
  24. 24.1 + 2 + 3 + … + 44 =
  25. 25.1 + 2 + 3 + … + 58 =
  26. 26.1 + 2 + 3 + … + 29 =
  27. 27.1 + 2 + 3 + … + 89 =
  28. 28.1 + 3 + 5 + … + 41 =
  29. 29.1 + 2 + 3 + … + 7 =
  30. 30.1 + 2 + 3 + … + 6 =
  31. 31.1 + 2 + 3 + … + 99 =
  32. 32.1 + 2 + 3 + … + 31 =
  33. 33.1 + 2 + 3 + … + 26 =
  34. 34.1 + 2 + 3 + … + 52 =
  35. 35.1 + 2 + 3 + … + 77 =
  36. 36.1 + 2 + 3 + … + 67 =
  37. 37.1 + 2 + 3 + … + 87 =
  38. 38.1 + 2 + 3 + … + 34 =
  39. 39.1 + 2 + 3 + … + 68 =
  40. 40.1 + 3 + 5 + … + 25 =

Answer key

  1. 36
  2. 4465
  3. 3655
  4. 55
  5. 5050
  6. 3570
  7. 378
  8. 25
  9. 2628
  10. 300
  11. 4095
  12. 4278
  13. 100
  14. 64
  15. 1326
  16. 4371
  17. 225
  18. 4560
  19. 946
  20. 2926
  21. 49
  22. 78
  23. 3081
  24. 990
  25. 1711
  26. 435
  27. 4005
  28. 441
  29. 28
  30. 21
  31. 4950
  32. 496
  33. 351
  34. 1378
  35. 3003
  36. 2278
  37. 3828
  38. 595
  39. 2346
  40. 169

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