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Sum of 1 to 100 Worksheet

Maths tricks trick 8: Add 1 to 100 in seconds · Set 914 · 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 + … + 13 =
  2. 2.1 + 3 + 5 + … + 29 =
  3. 3.1 + 2 + 3 + … + 37 =
  4. 4.1 + 3 + 5 + … + 27 =
  5. 5.1 + 2 + 3 + … + 70 =
  6. 6.1 + 2 + 3 + … + 84 =
  7. 7.1 + 2 + 3 + … + 65 =
  8. 8.1 + 3 + 5 + … + 33 =
  9. 9.1 + 2 + 3 + … + 98 =
  10. 10.1 + 3 + 5 + … + 47 =
  11. 11.1 + 2 + 3 + … + 32 =
  12. 12.1 + 2 + 3 + … + 12 =
  13. 13.1 + 2 + 3 + … + 97 =
  14. 14.1 + 2 + 3 + … + 33 =
  15. 15.1 + 2 + 3 + … + 10 =
  16. 16.1 + 2 + 3 + … + 52 =
  17. 17.1 + 2 + 3 + … + 38 =
  18. 18.1 + 2 + 3 + … + 99 =
  19. 19.1 + 3 + 5 + … + 31 =
  20. 20.1 + 2 + 3 + … + 53 =
  21. 21.1 + 2 + 3 + … + 34 =
  22. 22.1 + 2 + 3 + … + 95 =
  23. 23.1 + 2 + 3 + … + 59 =
  24. 24.1 + 2 + 3 + … + 100 =
  25. 25.1 + 2 + 3 + … + 44 =
  26. 26.1 + 2 + 3 + … + 83 =
  27. 27.1 + 2 + 3 + … + 15 =
  28. 28.1 + 2 + 3 + … + 45 =
  29. 29.1 + 2 + 3 + … + 8 =
  30. 30.1 + 2 + 3 + … + 48 =
  31. 31.1 + 2 + 3 + … + 18 =
  32. 32.1 + 2 + 3 + … + 72 =
  33. 33.1 + 2 + 3 + … + 9 =
  34. 34.1 + 2 + 3 + … + 76 =
  35. 35.1 + 2 + 3 + … + 80 =
  36. 36.1 + 2 + 3 + … + 68 =
  37. 37.1 + 2 + 3 + … + 73 =
  38. 38.1 + 3 + 5 + … + 23 =
  39. 39.1 + 3 + 5 + … + 17 =
  40. 40.1 + 2 + 3 + … + 29 =

Answer key

  1. 49
  2. 225
  3. 703
  4. 196
  5. 2485
  6. 3570
  7. 2145
  8. 289
  9. 4851
  10. 576
  11. 528
  12. 78
  13. 4753
  14. 561
  15. 55
  16. 1378
  17. 741
  18. 4950
  19. 256
  20. 1431
  21. 595
  22. 4560
  23. 1770
  24. 5050
  25. 990
  26. 3486
  27. 120
  28. 1035
  29. 36
  30. 1176
  31. 171
  32. 2628
  33. 45
  34. 2926
  35. 3240
  36. 2346
  37. 2701
  38. 144
  39. 81
  40. 435

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