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Sum of 1 to 100 Worksheet

Maths tricks trick 8: Add 1 to 100 in seconds · Set 455 · 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 + … + 23 =
  2. 2.1 + 3 + 5 + … + 49 =
  3. 3.1 + 3 + 5 + … + 45 =
  4. 4.1 + 2 + 3 + … + 93 =
  5. 5.1 + 2 + 3 + … + 92 =
  6. 6.1 + 2 + 3 + … + 44 =
  7. 7.1 + 3 + 5 + … + 27 =
  8. 8.1 + 2 + 3 + … + 11 =
  9. 9.1 + 2 + 3 + … + 63 =
  10. 10.1 + 2 + 3 + … + 70 =
  11. 11.1 + 2 + 3 + … + 17 =
  12. 12.1 + 2 + 3 + … + 75 =
  13. 13.1 + 2 + 3 + … + 24 =
  14. 14.1 + 2 + 3 + … + 6 =
  15. 15.1 + 2 + 3 + … + 100 =
  16. 16.1 + 2 + 3 + … + 45 =
  17. 17.1 + 2 + 3 + … + 25 =
  18. 18.1 + 2 + 3 + … + 67 =
  19. 19.1 + 3 + 5 + … + 21 =
  20. 20.1 + 3 + 5 + … + 17 =
  21. 21.1 + 3 + 5 + … + 15 =
  22. 22.1 + 2 + 3 + … + 12 =
  23. 23.1 + 2 + 3 + … + 27 =
  24. 24.1 + 2 + 3 + … + 69 =
  25. 25.1 + 2 + 3 + … + 84 =
  26. 26.1 + 2 + 3 + … + 43 =
  27. 27.1 + 3 + 5 + … + 47 =
  28. 28.1 + 2 + 3 + … + 71 =
  29. 29.1 + 2 + 3 + … + 26 =
  30. 30.1 + 2 + 3 + … + 23 =
  31. 31.1 + 2 + 3 + … + 20 =
  32. 32.1 + 2 + 3 + … + 78 =
  33. 33.1 + 3 + 5 + … + 37 =
  34. 34.1 + 2 + 3 + … + 19 =
  35. 35.1 + 2 + 3 + … + 85 =
  36. 36.1 + 2 + 3 + … + 32 =
  37. 37.1 + 2 + 3 + … + 80 =
  38. 38.1 + 3 + 5 + … + 25 =
  39. 39.1 + 2 + 3 + … + 7 =
  40. 40.1 + 2 + 3 + … + 54 =

Answer key

  1. 144
  2. 625
  3. 529
  4. 4371
  5. 4278
  6. 990
  7. 196
  8. 66
  9. 2016
  10. 2485
  11. 153
  12. 2850
  13. 300
  14. 21
  15. 5050
  16. 1035
  17. 325
  18. 2278
  19. 121
  20. 81
  21. 64
  22. 78
  23. 378
  24. 2415
  25. 3570
  26. 946
  27. 576
  28. 2556
  29. 351
  30. 276
  31. 210
  32. 3081
  33. 361
  34. 190
  35. 3655
  36. 528
  37. 3240
  38. 169
  39. 28
  40. 1485

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