You all have found some really awesome questions outside of my archive. 
I love it. I really like this factorial question about 30! 
It's easy to deal with the 0s, but then you have to be careful 
with the corresponding units digit. It all goes back to looking at the prime 
factorization of 30! The key is to pull out the appropriate # of 
2s in the prime factorization that create those 7 zeroes.

Great job! Grade = 6/6 - Arup