The first digit can be any one of four. (2, 4, 6, 8). For each of these ...
The second digit can be any one of four. (2, 4, 6, 8). For each of these ...
The third digit can be any one of four. (2, 4, 6, 8).
Total number of possibilities = (4 x 4 x 4) = 64 .
=============================
If you say that zero is also an even digit, then there are 5 choices
for the second and third digits.
The total number of possibilities is (4 x 5 x 5) = 100 .
