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Sum of 1 to 100 Worksheet

Maths tricks trick 8: Add 1 to 100 in seconds · Set 546 · 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 + … + 26 =
  2. 2.1 + 3 + 5 + … + 45 =
  3. 3.1 + 2 + 3 + … + 43 =
  4. 4.1 + 3 + 5 + … + 31 =
  5. 5.1 + 2 + 3 + … + 51 =
  6. 6.1 + 2 + 3 + … + 82 =
  7. 7.1 + 2 + 3 + … + 6 =
  8. 8.1 + 2 + 3 + … + 78 =
  9. 9.1 + 2 + 3 + … + 13 =
  10. 10.1 + 2 + 3 + … + 97 =
  11. 11.1 + 2 + 3 + … + 38 =
  12. 12.1 + 2 + 3 + … + 32 =
  13. 13.1 + 2 + 3 + … + 93 =
  14. 14.1 + 2 + 3 + … + 79 =
  15. 15.1 + 2 + 3 + … + 41 =
  16. 16.1 + 2 + 3 + … + 95 =
  17. 17.1 + 2 + 3 + … + 36 =
  18. 18.1 + 2 + 3 + … + 81 =
  19. 19.1 + 3 + 5 + … + 47 =
  20. 20.1 + 2 + 3 + … + 15 =
  21. 21.1 + 2 + 3 + … + 17 =
  22. 22.1 + 2 + 3 + … + 18 =
  23. 23.1 + 3 + 5 + … + 29 =
  24. 24.1 + 2 + 3 + … + 16 =
  25. 25.1 + 2 + 3 + … + 91 =
  26. 26.1 + 2 + 3 + … + 67 =
  27. 27.1 + 2 + 3 + … + 29 =
  28. 28.1 + 2 + 3 + … + 84 =
  29. 29.1 + 3 + 5 + … + 43 =
  30. 30.1 + 2 + 3 + … + 72 =
  31. 31.1 + 2 + 3 + … + 10 =
  32. 32.1 + 3 + 5 + … + 35 =
  33. 33.1 + 2 + 3 + … + 39 =
  34. 34.1 + 2 + 3 + … + 40 =
  35. 35.1 + 2 + 3 + … + 7 =
  36. 36.1 + 3 + 5 + … + 13 =
  37. 37.1 + 2 + 3 + … + 27 =
  38. 38.1 + 2 + 3 + … + 87 =
  39. 39.1 + 2 + 3 + … + 86 =
  40. 40.1 + 2 + 3 + … + 92 =

Answer key

  1. 351
  2. 529
  3. 946
  4. 256
  5. 1326
  6. 3403
  7. 21
  8. 3081
  9. 91
  10. 4753
  11. 741
  12. 528
  13. 4371
  14. 3160
  15. 861
  16. 4560
  17. 666
  18. 3321
  19. 576
  20. 120
  21. 153
  22. 171
  23. 225
  24. 136
  25. 4186
  26. 2278
  27. 435
  28. 3570
  29. 484
  30. 2628
  31. 55
  32. 324
  33. 780
  34. 820
  35. 28
  36. 49
  37. 378
  38. 3828
  39. 3741
  40. 4278

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