I've somewhat got this question down but I'm only half way.
How many $7$-digit even numbers less than $3,000,000$ can be formed using all the digits $1,2,2,3,5,5,6$?
So I figured that there's about $4$ possible approaches
$1$ _ _ _ _ _ $6$
$1$ _ _ _ _ _ $2$
$2$ _ _ _ _ _ $6$
$2$ _ _ _ _ _ $2$
How do I fill in the middle? I tried $5!$ and dividing out the similar factorials but I didn't get the right answer .