G1.3 Choose three digits from $1,2,4,6,7$ to construct three-digit numbers. Of these three-digit numbers, how many of them are divisible by 3 ?
$126,246,147,267$ are divisible by 3 .
The permutations of the digits of $126,246,147,267$ are also divisible by 3 .
Total number of such integers $=3!\times 4=24$