7. Variant 1.

Petya has seven cards with digits $2,2,3,4,5,6,8$. He wants to use all the cards to form the largest natural number divisible by 12. What number should he get?
Answer: 8654232.

Solution. Since the number is divisible by 12, it is also divisible by 4, which means the number formed by its last two digits is divisible by 4. Such a number cannot consist of the two smallest digits (22), but it can consist of 2 and 3, and it equals 32. Arranging the remaining digits in descending order, we get the number 8654232.