Assuming the functions compute the time in microseconds.

For n=50, we have:
  10000 · log₂ n = 56438.561... microseconds < 1 second
  100000 · n = 5000000 = 5 seconds
..which is reasonable, and:
  10 · 2^n = 11258999068426240 ≈ 357 years
  10 · n! = 304140932017133780436126081660647688443776415689605120000000000000 ≈ 9.6e51 years
..which is not.