NL-NWO 2012 Problem 5

The numbers $1$ to $12$ are arranged in a sequence. The number of ways this can be done equals $12 \times11 \times 10\times ...\times 1$ . We impose the condition that in the sequence there should be exactly one number that is smaller than the number directly preceding it. How many of the $12 \times11 \times 10\times ...\times 1$ sequences satisfy this condition?