There are 10 total numbers ( 0, 1, 2,3, 4, 5, 6, 7, 8, 9)
The first number cannot be an 8, so it can be 9 different numbers.
The second number can be any of 10 numbers.
The third number can also be any of 10 numbers.
The fourth number can only be even so it can be 0, 2 , 4, 6, 8, so any of 5 numbers.
To find the total combinations, multiply the available choices by each other:
9 x 10 x 10 x 5 = 4,500 different combinations.