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Sum of 1 to 100 Worksheet

Maths tricks trick 8: Add 1 to 100 in seconds · Set 941 · 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 + … + 21 =
  2. 2.1 + 2 + 3 + … + 72 =
  3. 3.1 + 2 + 3 + … + 85 =
  4. 4.1 + 2 + 3 + … + 9 =
  5. 5.1 + 2 + 3 + … + 7 =
  6. 6.1 + 2 + 3 + … + 81 =
  7. 7.1 + 2 + 3 + … + 68 =
  8. 8.1 + 3 + 5 + … + 19 =
  9. 9.1 + 2 + 3 + … + 67 =
  10. 10.1 + 2 + 3 + … + 31 =
  11. 11.1 + 2 + 3 + … + 60 =
  12. 12.1 + 2 + 3 + … + 59 =
  13. 13.1 + 2 + 3 + … + 53 =
  14. 14.1 + 2 + 3 + … + 94 =
  15. 15.1 + 2 + 3 + … + 84 =
  16. 16.1 + 3 + 5 + … + 49 =
  17. 17.1 + 3 + 5 + … + 25 =
  18. 18.1 + 3 + 5 + … + 17 =
  19. 19.1 + 2 + 3 + … + 76 =
  20. 20.1 + 3 + 5 + … + 35 =
  21. 21.1 + 2 + 3 + … + 99 =
  22. 22.1 + 3 + 5 + … + 37 =
  23. 23.1 + 2 + 3 + … + 71 =
  24. 24.1 + 2 + 3 + … + 73 =
  25. 25.1 + 3 + 5 + … + 43 =
  26. 26.1 + 3 + 5 + … + 33 =
  27. 27.1 + 2 + 3 + … + 27 =
  28. 28.1 + 2 + 3 + … + 65 =
  29. 29.1 + 2 + 3 + … + 6 =
  30. 30.1 + 2 + 3 + … + 33 =
  31. 31.1 + 2 + 3 + … + 30 =
  32. 32.1 + 2 + 3 + … + 25 =
  33. 33.1 + 3 + 5 + … + 31 =
  34. 34.1 + 2 + 3 + … + 100 =
  35. 35.1 + 2 + 3 + … + 37 =
  36. 36.1 + 3 + 5 + … + 41 =
  37. 37.1 + 2 + 3 + … + 17 =
  38. 38.1 + 2 + 3 + … + 46 =
  39. 39.1 + 2 + 3 + … + 18 =
  40. 40.1 + 2 + 3 + … + 61 =

Answer key

  1. 121
  2. 2628
  3. 3655
  4. 45
  5. 28
  6. 3321
  7. 2346
  8. 100
  9. 2278
  10. 496
  11. 1830
  12. 1770
  13. 1431
  14. 4465
  15. 3570
  16. 625
  17. 169
  18. 81
  19. 2926
  20. 324
  21. 4950
  22. 361
  23. 2556
  24. 2701
  25. 484
  26. 289
  27. 378
  28. 2145
  29. 21
  30. 561
  31. 465
  32. 325
  33. 256
  34. 5050
  35. 703
  36. 441
  37. 153
  38. 1081
  39. 171
  40. 1891

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