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Sum of 1 to 100 Worksheet

Maths tricks trick 8: Add 1 to 100 in seconds · Set 133 · 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 + 2 + 3 + … + 64 =
  2. 2.1 + 2 + 3 + … + 79 =
  3. 3.1 + 2 + 3 + … + 63 =
  4. 4.1 + 2 + 3 + … + 90 =
  5. 5.1 + 3 + 5 + … + 9 =
  6. 6.1 + 2 + 3 + … + 59 =
  7. 7.1 + 2 + 3 + … + 46 =
  8. 8.1 + 2 + 3 + … + 67 =
  9. 9.1 + 3 + 5 + … + 17 =
  10. 10.1 + 3 + 5 + … + 45 =
  11. 11.1 + 2 + 3 + … + 6 =
  12. 12.1 + 2 + 3 + … + 35 =
  13. 13.1 + 2 + 3 + … + 96 =
  14. 14.1 + 2 + 3 + … + 14 =
  15. 15.1 + 3 + 5 + … + 49 =
  16. 16.1 + 2 + 3 + … + 48 =
  17. 17.1 + 3 + 5 + … + 11 =
  18. 18.1 + 2 + 3 + … + 56 =
  19. 19.1 + 3 + 5 + … + 35 =
  20. 20.1 + 2 + 3 + … + 95 =
  21. 21.1 + 2 + 3 + … + 62 =
  22. 22.1 + 2 + 3 + … + 52 =
  23. 23.1 + 2 + 3 + … + 53 =
  24. 24.1 + 2 + 3 + … + 61 =
  25. 25.1 + 2 + 3 + … + 98 =
  26. 26.1 + 2 + 3 + … + 36 =
  27. 27.1 + 2 + 3 + … + 57 =
  28. 28.1 + 2 + 3 + … + 80 =
  29. 29.1 + 2 + 3 + … + 84 =
  30. 30.1 + 2 + 3 + … + 58 =
  31. 31.1 + 2 + 3 + … + 76 =
  32. 32.1 + 2 + 3 + … + 31 =
  33. 33.1 + 2 + 3 + … + 94 =
  34. 34.1 + 3 + 5 + … + 39 =
  35. 35.1 + 3 + 5 + … + 43 =
  36. 36.1 + 2 + 3 + … + 27 =
  37. 37.1 + 2 + 3 + … + 78 =
  38. 38.1 + 2 + 3 + … + 13 =
  39. 39.1 + 3 + 5 + … + 25 =
  40. 40.1 + 3 + 5 + … + 27 =

Answer key

  1. 2080
  2. 3160
  3. 2016
  4. 4095
  5. 25
  6. 1770
  7. 1081
  8. 2278
  9. 81
  10. 529
  11. 21
  12. 630
  13. 4656
  14. 105
  15. 625
  16. 1176
  17. 36
  18. 1596
  19. 324
  20. 4560
  21. 1953
  22. 1378
  23. 1431
  24. 1891
  25. 4851
  26. 666
  27. 1653
  28. 3240
  29. 3570
  30. 1711
  31. 2926
  32. 496
  33. 4465
  34. 400
  35. 484
  36. 378
  37. 3081
  38. 91
  39. 169
  40. 196

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