(Python)  # replace triple dots by spaces

def a(n):

...if n<=1: return 1

...return 6*[1, 1, 2, 6, 4, 4, 4, 8, 4, 6][n%10]*3**(n/5%4)*a(n/5)%10

def a(n):
   if n<=1: return 1
   return 6*[1, 1, 2, 6, 4, 4, 4, 8, 4, 6][n%10]*3**(n/5%4)*a(n/5)%10

@DHMO def last_fact_n (n):
    start_time = time.time()
    "Return the last non-zero digit of N!"
    f2 = f5 = lznd_trailing_zeros(n)
    r = 1
    for i in range(1,n+1):
        while f2 > 0 and i%2 == 0:
            f2 -= 1
            i /= 2
        while f5 > 0 and i%5 == 0:
            f5 -= 1
            i /= 5
        r = (i*r) % 10
    print("It took {} ms".format((time.time() - start_time)*1000.0))
    return r

C:\Users\XXX>python
Python 3.5.1 (v3.5.1:37a07cee5969, Dec  6 2015, 01:38:48) [MSC v.1900 32 bit (In
tel)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> def a(n):
...     if n<=1: return 1
...     return 6*[1, 1, 2, 6, 4, 4, 4, 8, 4, 6][n%10]*3**(n//5%4)*a(n//5)%10
...
>>> a(6)
2
>>>