Question 1055461
.
what is the smallest number divisible by 10 and such that the factorial of this number is divisible by 10¹² ? 
a) 40     b) 50     c) 60     d) 80     e) 100  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~


<pre>
TABLE

The number n         5    10   15   20    25   30   40   45   50    55    60

n! is divisible by   5^1  5^2  5^3  5^4   5^6  5^7  5^8  5^9  5^11  5^12  5^13


The Table shows that  5! is divisible by 5 in degree 1.
                     10! is divisible by 5 in degree 2.
                     15! is divisible by 5 in degree 3,  and so on.
</pre>

<U>Answer</U>.   n=55.  There is no such an option in your list.