X is the largest prime number less than positive integer N. P is an integer such that P = X – 16. Also, Z = 1*2*…*P√P. If N is the first non-zero perfect square whose tens digit and units digit are same, How many different prime factors does Z have?  Choose the correct answer.
A) 4  B) 5  C) 6  D) 160  E) 320
If N is the first perfect square whose tens digit and units digit are same, then N=100.   X is the largest prime number less than positive integer N , then X is   97.   P is an integer such that P = X – 16.   So P=81   Z=(P^1/2)! = 9!   How many different prime factors does Z have?   4nswer 4 (2,3,5,7)   4NSWER:4
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X is the largest prime number less than positive integer N. P is an integer such that P = X – 16. Also, Z = 1*2*…*P√P. If N is the first non-zero perfect square whose tens digit and units digit are same, How many different prime factors does Z have?