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Sum of 1 to 100 Worksheet

Maths tricks trick 8: Add 1 to 100 in seconds · Set 35 · 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 + … + 27 =
  2. 2.1 + 3 + 5 + … + 37 =
  3. 3.1 + 2 + 3 + … + 48 =
  4. 4.1 + 2 + 3 + … + 59 =
  5. 5.1 + 2 + 3 + … + 34 =
  6. 6.1 + 3 + 5 + … + 25 =
  7. 7.1 + 2 + 3 + … + 73 =
  8. 8.1 + 2 + 3 + … + 32 =
  9. 9.1 + 2 + 3 + … + 44 =
  10. 10.1 + 2 + 3 + … + 30 =
  11. 11.1 + 3 + 5 + … + 31 =
  12. 12.1 + 2 + 3 + … + 10 =
  13. 13.1 + 2 + 3 + … + 42 =
  14. 14.1 + 2 + 3 + … + 12 =
  15. 15.1 + 2 + 3 + … + 96 =
  16. 16.1 + 2 + 3 + … + 70 =
  17. 17.1 + 2 + 3 + … + 37 =
  18. 18.1 + 2 + 3 + … + 63 =
  19. 19.1 + 2 + 3 + … + 77 =
  20. 20.1 + 3 + 5 + … + 43 =
  21. 21.1 + 2 + 3 + … + 43 =
  22. 22.1 + 2 + 3 + … + 21 =
  23. 23.1 + 2 + 3 + … + 78 =
  24. 24.1 + 2 + 3 + … + 60 =
  25. 25.1 + 2 + 3 + … + 89 =
  26. 26.1 + 2 + 3 + … + 27 =
  27. 27.1 + 2 + 3 + … + 29 =
  28. 28.1 + 2 + 3 + … + 6 =
  29. 29.1 + 3 + 5 + … + 15 =
  30. 30.1 + 2 + 3 + … + 31 =
  31. 31.1 + 2 + 3 + … + 19 =
  32. 32.1 + 2 + 3 + … + 50 =
  33. 33.1 + 2 + 3 + … + 13 =
  34. 34.1 + 2 + 3 + … + 74 =
  35. 35.1 + 2 + 3 + … + 72 =
  36. 36.1 + 2 + 3 + … + 38 =
  37. 37.1 + 2 + 3 + … + 39 =
  38. 38.1 + 3 + 5 + … + 39 =
  39. 39.1 + 3 + 5 + … + 29 =
  40. 40.1 + 2 + 3 + … + 97 =

Answer key

  1. 196
  2. 361
  3. 1176
  4. 1770
  5. 595
  6. 169
  7. 2701
  8. 528
  9. 990
  10. 465
  11. 256
  12. 55
  13. 903
  14. 78
  15. 4656
  16. 2485
  17. 703
  18. 2016
  19. 3003
  20. 484
  21. 946
  22. 231
  23. 3081
  24. 1830
  25. 4005
  26. 378
  27. 435
  28. 21
  29. 64
  30. 496
  31. 190
  32. 1275
  33. 91
  34. 2775
  35. 2628
  36. 741
  37. 780
  38. 400
  39. 225
  40. 4753

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