Number of Permutations = n!
where n! represents the factorial of n, which is the product of all positive integers up to n.
In this case, n = 9, so the number of permutations for 9 performances is:
Number of Permutations = 9!
Calculating 9! by multiplying all the integers from 1 to 9, we get:
9! = 9 x 8 x 7 x 6 x 5 x 4 x 3 x 2 x 1 = 362,880
Therefore, there are 362,880 ways that 9 performances at a piano recital can be ordered.