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Sum of 1 to 100 Worksheet

Maths tricks trick 8: Add 1 to 100 in seconds · Set 8 · 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 + … + 45 =
  2. 2.1 + 3 + 5 + … + 43 =
  3. 3.1 + 2 + 3 + … + 72 =
  4. 4.1 + 2 + 3 + … + 83 =
  5. 5.1 + 2 + 3 + … + 100 =
  6. 6.1 + 2 + 3 + … + 90 =
  7. 7.1 + 2 + 3 + … + 62 =
  8. 8.1 + 3 + 5 + … + 17 =
  9. 9.1 + 3 + 5 + … + 13 =
  10. 10.1 + 2 + 3 + … + 97 =
  11. 11.1 + 2 + 3 + … + 43 =
  12. 12.1 + 2 + 3 + … + 75 =
  13. 13.1 + 2 + 3 + … + 11 =
  14. 14.1 + 3 + 5 + … + 47 =
  15. 15.1 + 2 + 3 + … + 79 =
  16. 16.1 + 2 + 3 + … + 49 =
  17. 17.1 + 2 + 3 + … + 24 =
  18. 18.1 + 2 + 3 + … + 36 =
  19. 19.1 + 2 + 3 + … + 52 =
  20. 20.1 + 2 + 3 + … + 93 =
  21. 21.1 + 2 + 3 + … + 63 =
  22. 22.1 + 3 + 5 + … + 23 =
  23. 23.1 + 2 + 3 + … + 76 =
  24. 24.1 + 2 + 3 + … + 68 =
  25. 25.1 + 2 + 3 + … + 19 =
  26. 26.1 + 2 + 3 + … + 30 =
  27. 27.1 + 2 + 3 + … + 38 =
  28. 28.1 + 3 + 5 + … + 31 =
  29. 29.1 + 2 + 3 + … + 44 =
  30. 30.1 + 2 + 3 + … + 10 =
  31. 31.1 + 2 + 3 + … + 53 =
  32. 32.1 + 2 + 3 + … + 96 =
  33. 33.1 + 2 + 3 + … + 42 =
  34. 34.1 + 3 + 5 + … + 9 =
  35. 35.1 + 2 + 3 + … + 48 =
  36. 36.1 + 2 + 3 + … + 54 =
  37. 37.1 + 2 + 3 + … + 89 =
  38. 38.1 + 2 + 3 + … + 41 =
  39. 39.1 + 2 + 3 + … + 23 =
  40. 40.1 + 2 + 3 + … + 29 =

Answer key

  1. 529
  2. 484
  3. 2628
  4. 3486
  5. 5050
  6. 4095
  7. 1953
  8. 81
  9. 49
  10. 4753
  11. 946
  12. 2850
  13. 66
  14. 576
  15. 3160
  16. 1225
  17. 300
  18. 666
  19. 1378
  20. 4371
  21. 2016
  22. 144
  23. 2926
  24. 2346
  25. 190
  26. 465
  27. 741
  28. 256
  29. 990
  30. 55
  31. 1431
  32. 4656
  33. 903
  34. 25
  35. 1176
  36. 1485
  37. 4005
  38. 861
  39. 276
  40. 435

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