the number of trailing zeros in a factorial of a given number - Ruby

Question

Having a little trouble trying calculate the number of trailing zeros in a factorial of a given number. This is one of the challenges from Codewars- can\'t get mine to pass.

Answer 1

As per the explanation given by @spundan and apart from @cary's code you can find number of trailing zero by just very simple and efficient way..see below code..

def zeros(n)
    ret = 0
    while n > 0 do 
        ret += n / 5
        n = n/5
    end
    ret
end

For example zeros(100000000) this will give you output -> 24999999
With the time Time Elapsed -> 5.0453e-05(Just See 5.0453e-05 )
This is the part of even milliseconds.