What is the log of 40000?

Answer 1

It is the value that when the base you have chosen for your log is raised to that value gives 40,000

log with no base indicated means log to any base, thought calculators often use it to mean logs to base 10, which is often abbreviated to lg

lg(40,000) = log{base 10} 40,000 ≈ 4.6021

ln(40,000) = log{base e} 40,000 ≈10.5966

Answer 2

It is approx 4.6021