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 required percentage of prime numbers is 0.  

Edited on September 6, 2023, 8:02 am

Posted by K Sengupta on 2008-02-26 22:31:03