The easiest way to do this is to write out 6 spaces like this.
_ * _ * _ * _ * _ * _ Now, in each space we need to find how many possible numbers could work.
Since the first space cannot be zero, that leaves us with 2,4,6,8 as even numbers, which is 4 even numbers.
So, we get 4*_*_*_*_*_
In all the other spaces, we CAN use 0 which means there are 5 even numbers. So, we fill in all the other spots and get:
4*5*5*5*5*5
Multiply it out and you get 12,500 different possibilities.