Number properties.

[patcheko80]

Dear All.
Here is a toughie that I came across in my last test. Had no clue on how to get it right.
Any help?

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 = 3x5x5.
How many two digits integer has length of 6?

A. None
B. One
C. Two
D. Three
E. Four

The correct answer is C

[davegerstel]

Well, the smallest possible number that has 6 prime numbers in its prime factorization is 2x2x2x2x2x2 which equals 64. The next smallest number that has 6 prime factors is 2x2x2x2x2x3 which equals 96. The next smallest number is 2x2x2x2x2x4 which is over 100. So only two numbers are under 100

[RonPurewal]

search the forum, please ... thanks

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