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Sum of 1 to 100 Worksheet

Maths tricks trick 8: Add 1 to 100 in seconds · Set 501 · 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 + … + 37 =
  2. 2.1 + 3 + 5 + … + 21 =
  3. 3.1 + 2 + 3 + … + 10 =
  4. 4.1 + 2 + 3 + … + 33 =
  5. 5.1 + 2 + 3 + … + 18 =
  6. 6.1 + 2 + 3 + … + 91 =
  7. 7.1 + 2 + 3 + … + 13 =
  8. 8.1 + 2 + 3 + … + 75 =
  9. 9.1 + 2 + 3 + … + 43 =
  10. 10.1 + 2 + 3 + … + 7 =
  11. 11.1 + 2 + 3 + … + 81 =
  12. 12.1 + 2 + 3 + … + 30 =
  13. 13.1 + 3 + 5 + … + 9 =
  14. 14.1 + 2 + 3 + … + 96 =
  15. 15.1 + 3 + 5 + … + 27 =
  16. 16.1 + 3 + 5 + … + 23 =
  17. 17.1 + 2 + 3 + … + 12 =
  18. 18.1 + 2 + 3 + … + 25 =
  19. 19.1 + 2 + 3 + … + 72 =
  20. 20.1 + 2 + 3 + … + 40 =
  21. 21.1 + 2 + 3 + … + 28 =
  22. 22.1 + 2 + 3 + … + 6 =
  23. 23.1 + 2 + 3 + … + 83 =
  24. 24.1 + 2 + 3 + … + 54 =
  25. 25.1 + 3 + 5 + … + 33 =
  26. 26.1 + 3 + 5 + … + 17 =
  27. 27.1 + 2 + 3 + … + 87 =
  28. 28.1 + 3 + 5 + … + 45 =
  29. 29.1 + 2 + 3 + … + 44 =
  30. 30.1 + 2 + 3 + … + 78 =
  31. 31.1 + 3 + 5 + … + 25 =
  32. 32.1 + 2 + 3 + … + 97 =
  33. 33.1 + 2 + 3 + … + 73 =
  34. 34.1 + 2 + 3 + … + 52 =
  35. 35.1 + 3 + 5 + … + 31 =
  36. 36.1 + 2 + 3 + … + 9 =
  37. 37.1 + 2 + 3 + … + 67 =
  38. 38.1 + 2 + 3 + … + 56 =
  39. 39.1 + 3 + 5 + … + 13 =
  40. 40.1 + 2 + 3 + … + 45 =

Answer key

  1. 361
  2. 121
  3. 55
  4. 561
  5. 171
  6. 4186
  7. 91
  8. 2850
  9. 946
  10. 28
  11. 3321
  12. 465
  13. 25
  14. 4656
  15. 196
  16. 144
  17. 78
  18. 325
  19. 2628
  20. 820
  21. 406
  22. 21
  23. 3486
  24. 1485
  25. 289
  26. 81
  27. 3828
  28. 529
  29. 990
  30. 3081
  31. 169
  32. 4753
  33. 2701
  34. 1378
  35. 256
  36. 45
  37. 2278
  38. 1596
  39. 49
  40. 1035

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