x is a positive integer such that the sum of its digits times 5 equals itself. What is x?

Question

What is the least positive integer n that can be placed in the following expression:

n!(n+1)!(2n+1)! - 1

and yields a number ending with thirty digits of 9's.

Answer 1

if x = 45
then 4 + 5 = 9
9 x 5 = 45.