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Sum of 1 to 100 Worksheet

Maths tricks trick 8: Add 1 to 100 in seconds · Set 558 · 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 + … + 42 =
  2. 2.1 + 2 + 3 + … + 29 =
  3. 3.1 + 2 + 3 + … + 37 =
  4. 4.1 + 3 + 5 + … + 21 =
  5. 5.1 + 2 + 3 + … + 95 =
  6. 6.1 + 2 + 3 + … + 64 =
  7. 7.1 + 3 + 5 + … + 15 =
  8. 8.1 + 2 + 3 + … + 98 =
  9. 9.1 + 3 + 5 + … + 45 =
  10. 10.1 + 3 + 5 + … + 31 =
  11. 11.1 + 2 + 3 + … + 65 =
  12. 12.1 + 3 + 5 + … + 19 =
  13. 13.1 + 2 + 3 + … + 27 =
  14. 14.1 + 2 + 3 + … + 36 =
  15. 15.1 + 2 + 3 + … + 93 =
  16. 16.1 + 3 + 5 + … + 37 =
  17. 17.1 + 2 + 3 + … + 46 =
  18. 18.1 + 2 + 3 + … + 73 =
  19. 19.1 + 2 + 3 + … + 86 =
  20. 20.1 + 3 + 5 + … + 35 =
  21. 21.1 + 3 + 5 + … + 23 =
  22. 22.1 + 2 + 3 + … + 94 =
  23. 23.1 + 2 + 3 + … + 74 =
  24. 24.1 + 2 + 3 + … + 10 =
  25. 25.1 + 3 + 5 + … + 47 =
  26. 26.1 + 2 + 3 + … + 17 =
  27. 27.1 + 2 + 3 + … + 23 =
  28. 28.1 + 2 + 3 + … + 88 =
  29. 29.1 + 2 + 3 + … + 12 =
  30. 30.1 + 2 + 3 + … + 32 =
  31. 31.1 + 2 + 3 + … + 41 =
  32. 32.1 + 2 + 3 + … + 14 =
  33. 33.1 + 2 + 3 + … + 75 =
  34. 34.1 + 2 + 3 + … + 22 =
  35. 35.1 + 3 + 5 + … + 11 =
  36. 36.1 + 2 + 3 + … + 82 =
  37. 37.1 + 2 + 3 + … + 18 =
  38. 38.1 + 3 + 5 + … + 29 =
  39. 39.1 + 2 + 3 + … + 71 =
  40. 40.1 + 2 + 3 + … + 84 =

Answer key

  1. 903
  2. 435
  3. 703
  4. 121
  5. 4560
  6. 2080
  7. 64
  8. 4851
  9. 529
  10. 256
  11. 2145
  12. 100
  13. 378
  14. 666
  15. 4371
  16. 361
  17. 1081
  18. 2701
  19. 3741
  20. 324
  21. 144
  22. 4465
  23. 2775
  24. 55
  25. 576
  26. 153
  27. 276
  28. 3916
  29. 78
  30. 528
  31. 861
  32. 105
  33. 2850
  34. 253
  35. 36
  36. 3403
  37. 171
  38. 225
  39. 2556
  40. 3570

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