Answer
See below.
Work Step by Step
According to the Multiplication Principle, if we have $p$ selections for the first choice, $q$ selections for the second choice, then we have $p\cdot q$ different ways of selections and so on for more choices...
Here we have $26-2=24$ possibilities for the first character, $10-1=9$ options for the first number and $10$ possibilities for the other three numbers, thus the number of possibilities is $24\cdot9\cdot10^3=216000$
