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Sum of 1 to 100 Worksheet

Maths tricks trick 8: Add 1 to 100 in seconds · Set 222 · 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 + … + 45 =
  2. 2.1 + 2 + 3 + … + 26 =
  3. 3.1 + 2 + 3 + … + 9 =
  4. 4.1 + 2 + 3 + … + 90 =
  5. 5.1 + 2 + 3 + … + 51 =
  6. 6.1 + 3 + 5 + … + 11 =
  7. 7.1 + 2 + 3 + … + 41 =
  8. 8.1 + 2 + 3 + … + 6 =
  9. 9.1 + 2 + 3 + … + 71 =
  10. 10.1 + 2 + 3 + … + 65 =
  11. 11.1 + 2 + 3 + … + 78 =
  12. 12.1 + 2 + 3 + … + 59 =
  13. 13.1 + 2 + 3 + … + 67 =
  14. 14.1 + 2 + 3 + … + 23 =
  15. 15.1 + 2 + 3 + … + 38 =
  16. 16.1 + 3 + 5 + … + 19 =
  17. 17.1 + 2 + 3 + … + 50 =
  18. 18.1 + 2 + 3 + … + 39 =
  19. 19.1 + 2 + 3 + … + 44 =
  20. 20.1 + 3 + 5 + … + 25 =
  21. 21.1 + 2 + 3 + … + 86 =
  22. 22.1 + 3 + 5 + … + 49 =
  23. 23.1 + 2 + 3 + … + 57 =
  24. 24.1 + 2 + 3 + … + 46 =
  25. 25.1 + 2 + 3 + … + 96 =
  26. 26.1 + 2 + 3 + … + 48 =
  27. 27.1 + 2 + 3 + … + 8 =
  28. 28.1 + 2 + 3 + … + 75 =
  29. 29.1 + 2 + 3 + … + 55 =
  30. 30.1 + 3 + 5 + … + 13 =
  31. 31.1 + 2 + 3 + … + 54 =
  32. 32.1 + 2 + 3 + … + 73 =
  33. 33.1 + 2 + 3 + … + 85 =
  34. 34.1 + 2 + 3 + … + 87 =
  35. 35.1 + 2 + 3 + … + 7 =
  36. 36.1 + 2 + 3 + … + 80 =
  37. 37.1 + 2 + 3 + … + 92 =
  38. 38.1 + 2 + 3 + … + 94 =
  39. 39.1 + 2 + 3 + … + 82 =
  40. 40.1 + 2 + 3 + … + 15 =

Answer key

  1. 1035
  2. 351
  3. 45
  4. 4095
  5. 1326
  6. 36
  7. 861
  8. 21
  9. 2556
  10. 2145
  11. 3081
  12. 1770
  13. 2278
  14. 276
  15. 741
  16. 100
  17. 1275
  18. 780
  19. 990
  20. 169
  21. 3741
  22. 625
  23. 1653
  24. 1081
  25. 4656
  26. 1176
  27. 36
  28. 2850
  29. 1540
  30. 49
  31. 1485
  32. 2701
  33. 3655
  34. 3828
  35. 28
  36. 3240
  37. 4278
  38. 4465
  39. 3403
  40. 120

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