"""
Write a program that will calculate the number of trailing zeros in a factorial of a given number.

N! = 1 * 2 * 3 * ... * N

Be careful 1000! has 2568 digits...

For more info, see: http://mathworld.wolfram.com/Factorial.html

Examples
zeros(6) = 1
# 6! = 1 * 2 * 3 * 4 * 5 * 6 = 720 --> 1 trailing zero

zeros(12) = 2
# 12! = 479001600 --> 2 trailing zeros
Hint: You're not meant to calculate the factorial. Find another way to find the number of zeros.
"""

def zeros(n):
    count = 0
    i=5
    while (n/i>=1): 
        count += int(n/i) 
        i *= 5

    return int(count)
