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Sum of 1 to 100 Worksheet

Maths tricks trick 8: Add 1 to 100 in seconds · Set 392 · 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 + … + 61 =
  2. 2.1 + 2 + 3 + … + 36 =
  3. 3.1 + 3 + 5 + … + 9 =
  4. 4.1 + 2 + 3 + … + 56 =
  5. 5.1 + 2 + 3 + … + 11 =
  6. 6.1 + 2 + 3 + … + 65 =
  7. 7.1 + 2 + 3 + … + 97 =
  8. 8.1 + 2 + 3 + … + 84 =
  9. 9.1 + 2 + 3 + … + 26 =
  10. 10.1 + 2 + 3 + … + 83 =
  11. 11.1 + 2 + 3 + … + 53 =
  12. 12.1 + 2 + 3 + … + 62 =
  13. 13.1 + 2 + 3 + … + 44 =
  14. 14.1 + 3 + 5 + … + 23 =
  15. 15.1 + 2 + 3 + … + 58 =
  16. 16.1 + 2 + 3 + … + 6 =
  17. 17.1 + 3 + 5 + … + 47 =
  18. 18.1 + 2 + 3 + … + 31 =
  19. 19.1 + 2 + 3 + … + 48 =
  20. 20.1 + 3 + 5 + … + 27 =
  21. 21.1 + 2 + 3 + … + 19 =
  22. 22.1 + 2 + 3 + … + 70 =
  23. 23.1 + 3 + 5 + … + 25 =
  24. 24.1 + 2 + 3 + … + 14 =
  25. 25.1 + 3 + 5 + … + 19 =
  26. 26.1 + 2 + 3 + … + 85 =
  27. 27.1 + 3 + 5 + … + 11 =
  28. 28.1 + 2 + 3 + … + 92 =
  29. 29.1 + 3 + 5 + … + 15 =
  30. 30.1 + 2 + 3 + … + 96 =
  31. 31.1 + 2 + 3 + … + 75 =
  32. 32.1 + 3 + 5 + … + 21 =
  33. 33.1 + 2 + 3 + … + 55 =
  34. 34.1 + 2 + 3 + … + 79 =
  35. 35.1 + 2 + 3 + … + 87 =
  36. 36.1 + 2 + 3 + … + 13 =
  37. 37.1 + 2 + 3 + … + 32 =
  38. 38.1 + 3 + 5 + … + 17 =
  39. 39.1 + 2 + 3 + … + 54 =
  40. 40.1 + 2 + 3 + … + 60 =

Answer key

  1. 1891
  2. 666
  3. 25
  4. 1596
  5. 66
  6. 2145
  7. 4753
  8. 3570
  9. 351
  10. 3486
  11. 1431
  12. 1953
  13. 990
  14. 144
  15. 1711
  16. 21
  17. 576
  18. 496
  19. 1176
  20. 196
  21. 190
  22. 2485
  23. 169
  24. 105
  25. 100
  26. 3655
  27. 36
  28. 4278
  29. 64
  30. 4656
  31. 2850
  32. 121
  33. 1540
  34. 3160
  35. 3828
  36. 91
  37. 528
  38. 81
  39. 1485
  40. 1830

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