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Sum of 1 to 100 Worksheet

Maths tricks trick 8: Add 1 to 100 in seconds · Set 218 · 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 + … + 37 =
  2. 2.1 + 2 + 3 + … + 25 =
  3. 3.1 + 3 + 5 + … + 29 =
  4. 4.1 + 2 + 3 + … + 30 =
  5. 5.1 + 2 + 3 + … + 14 =
  6. 6.1 + 2 + 3 + … + 23 =
  7. 7.1 + 2 + 3 + … + 40 =
  8. 8.1 + 2 + 3 + … + 51 =
  9. 9.1 + 3 + 5 + … + 49 =
  10. 10.1 + 2 + 3 + … + 72 =
  11. 11.1 + 3 + 5 + … + 31 =
  12. 12.1 + 2 + 3 + … + 98 =
  13. 13.1 + 2 + 3 + … + 75 =
  14. 14.1 + 3 + 5 + … + 17 =
  15. 15.1 + 2 + 3 + … + 79 =
  16. 16.1 + 2 + 3 + … + 89 =
  17. 17.1 + 2 + 3 + … + 50 =
  18. 18.1 + 3 + 5 + … + 15 =
  19. 19.1 + 2 + 3 + … + 54 =
  20. 20.1 + 3 + 5 + … + 13 =
  21. 21.1 + 2 + 3 + … + 65 =
  22. 22.1 + 2 + 3 + … + 38 =
  23. 23.1 + 3 + 5 + … + 23 =
  24. 24.1 + 3 + 5 + … + 9 =
  25. 25.1 + 2 + 3 + … + 84 =
  26. 26.1 + 2 + 3 + … + 13 =
  27. 27.1 + 2 + 3 + … + 73 =
  28. 28.1 + 3 + 5 + … + 45 =
  29. 29.1 + 2 + 3 + … + 11 =
  30. 30.1 + 2 + 3 + … + 80 =
  31. 31.1 + 2 + 3 + … + 81 =
  32. 32.1 + 2 + 3 + … + 27 =
  33. 33.1 + 2 + 3 + … + 68 =
  34. 34.1 + 2 + 3 + … + 59 =
  35. 35.1 + 3 + 5 + … + 41 =
  36. 36.1 + 2 + 3 + … + 39 =
  37. 37.1 + 2 + 3 + … + 57 =
  38. 38.1 + 2 + 3 + … + 32 =
  39. 39.1 + 2 + 3 + … + 48 =
  40. 40.1 + 3 + 5 + … + 39 =

Answer key

  1. 361
  2. 325
  3. 225
  4. 465
  5. 105
  6. 276
  7. 820
  8. 1326
  9. 625
  10. 2628
  11. 256
  12. 4851
  13. 2850
  14. 81
  15. 3160
  16. 4005
  17. 1275
  18. 64
  19. 1485
  20. 49
  21. 2145
  22. 741
  23. 144
  24. 25
  25. 3570
  26. 91
  27. 2701
  28. 529
  29. 66
  30. 3240
  31. 3321
  32. 378
  33. 2346
  34. 1770
  35. 441
  36. 780
  37. 1653
  38. 528
  39. 1176
  40. 400

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