9===6===4===2 The figure above show an example of a 4-digit identification code used by a certain bank for its customers.

9===6===4===2The figure above show an example of a 4-digit identification code used by a certain bank for its customers. If the digits in the code must appear in descending numerical order, not using zero and no digit can be used more than once, what is the difference between the largest and the smallest possible codes?