There are 362,880 different numbers that use the digits 1 to 9 exactly once (like 187,432,569).

Of these, what percentage are prime numbers?

For any given number that use the digits 1 to 9 exactly once, the sum of the digits is 45, which is divisible by 9. Accordingly, all the numbers having this property are divisible by 9 and cannot be primes.

Consequently, the reuired percentage of prime numbers is 0.

*Edited on ***February 26, 2008, 11:38 pm**