Subcategories

• Day 5

  Base Conversion Factorial Mod 314 The Biggest Factor A String of 2's
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  S

  10^n mod 7 is congruent to iii.) 3^n mod 7 but also congruent to v.) 17^n mod 7. They both should be correct but only iii.) is. Must be fixed

• Day 6

  Factorize 9991 Finding the Sum of Digits A Proof About Primes Base 10 to Base 9
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  In the video, the text question says 77 is in base 9, which is not true when compared to what Poh-Shen-Loh wrote and what the problem answer suggests.

• Day 7

  A Cube and a Square Find a Prime 1's and 0's Bonus: Constructing a Set of Nonprimes
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  Since 2021=2025-4=45^2-2^2, which means that 2021 can be written as (45+2)(45-2)=43*47. It's more faster than guessing the numbers and it's more easy to memorize. Although not all numbers can be solved that way

• Day 8

  Mod 17 Find All Solutions Revisiting GCDs
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  T

  a=4
  b=2
  Then gcd(a, b)=2 and gcd(a, 2b)=4!!!