For any positive integer n, the length of n is defined as the number of prime factors whose product is n. For example, the length of 75 is 3, since 75 = 3 * 5 * 5. How many two-digit positive integers have length 6?	Choose the correct answer:
A) None
B) One
C) Two
D) Three
E) Four
The best (quickest) way I can think of to get the answer, is start with 2^6, then move on from there.   2^6=64   2^5*3=96   Obviously 2^5*5 will be more than 2 digits, as will 2^4*3^2. So 64 and 96 are it.   Answer is 2 (Two).
<result>C</result>
For any positive integer n, the length of n is defined as the number of prime factors whose product is n. For example, the length of 75 is 3, since 75 = 3 * 5 * 5. How many two-digit positive integers have length 6?