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Sum of 1 to 100 Worksheet

Maths tricks trick 8: Add 1 to 100 in seconds · Set 788 · 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 + … + 37 =
  2. 2.1 + 2 + 3 + … + 10 =
  3. 3.1 + 2 + 3 + … + 14 =
  4. 4.1 + 2 + 3 + … + 24 =
  5. 5.1 + 3 + 5 + … + 49 =
  6. 6.1 + 2 + 3 + … + 53 =
  7. 7.1 + 2 + 3 + … + 17 =
  8. 8.1 + 3 + 5 + … + 31 =
  9. 9.1 + 2 + 3 + … + 84 =
  10. 10.1 + 2 + 3 + … + 63 =
  11. 11.1 + 3 + 5 + … + 13 =
  12. 12.1 + 2 + 3 + … + 75 =
  13. 13.1 + 2 + 3 + … + 45 =
  14. 14.1 + 2 + 3 + … + 30 =
  15. 15.1 + 2 + 3 + … + 79 =
  16. 16.1 + 2 + 3 + … + 49 =
  17. 17.1 + 2 + 3 + … + 93 =
  18. 18.1 + 2 + 3 + … + 19 =
  19. 19.1 + 3 + 5 + … + 11 =
  20. 20.1 + 3 + 5 + … + 29 =
  21. 21.1 + 2 + 3 + … + 23 =
  22. 22.1 + 3 + 5 + … + 19 =
  23. 23.1 + 3 + 5 + … + 17 =
  24. 24.1 + 3 + 5 + … + 25 =
  25. 25.1 + 2 + 3 + … + 40 =
  26. 26.1 + 2 + 3 + … + 80 =
  27. 27.1 + 3 + 5 + … + 35 =
  28. 28.1 + 2 + 3 + … + 22 =
  29. 29.1 + 2 + 3 + … + 12 =
  30. 30.1 + 2 + 3 + … + 76 =
  31. 31.1 + 2 + 3 + … + 61 =
  32. 32.1 + 2 + 3 + … + 91 =
  33. 33.1 + 2 + 3 + … + 43 =
  34. 34.1 + 2 + 3 + … + 70 =
  35. 35.1 + 3 + 5 + … + 27 =
  36. 36.1 + 3 + 5 + … + 21 =
  37. 37.1 + 2 + 3 + … + 57 =
  38. 38.1 + 2 + 3 + … + 27 =
  39. 39.1 + 3 + 5 + … + 15 =
  40. 40.1 + 2 + 3 + … + 33 =

Answer key

  1. 703
  2. 55
  3. 105
  4. 300
  5. 625
  6. 1431
  7. 153
  8. 256
  9. 3570
  10. 2016
  11. 49
  12. 2850
  13. 1035
  14. 465
  15. 3160
  16. 1225
  17. 4371
  18. 190
  19. 36
  20. 225
  21. 276
  22. 100
  23. 81
  24. 169
  25. 820
  26. 3240
  27. 324
  28. 253
  29. 78
  30. 2926
  31. 1891
  32. 4186
  33. 946
  34. 2485
  35. 196
  36. 121
  37. 1653
  38. 378
  39. 64
  40. 561

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