[Note #1][Math] Factorial

Note #1 (Guide to solve ProjectEuler)

Background knowledge: https://en.wikipedia.org/wiki/Factorial

• Legendre's formula (p-acid valuation): https://en.wikipedia.org/wiki/Legendre%27s_formula

Problems:

• Easy:
• https://uva.onlinejudge.org/index.php?option=onlinejudge&page=show_problem&problem=1002
• http://codeforces.com/problemset/problem/633/B?locale=en
• Normal:
• https://projecteuler.net/problem=160
• https://projecteuler.net/problem=288
• https://projecteuler.net/problem=320
• https://projecteuler.net/problem=381 (Wilson's theorem)
• https://projecteuler.net/problem=549
• Hard: (Unsolved):
• https://projecteuler.net/problem=383
• https://projecteuler.net/problem=592