9. (6 points) There are four cards, each with a number written on both sides. The first card has 0 and 1, the other three cards have 2 and 3, 4 and 5, 7 and 8, respectively. Now, if we randomly take out three of these cards and place them in a row, how many different three-digit numbers can be formed?
【Answer】Solution: $7 \times 6 \times 4=168$ (pieces). Therefore, the answer is: 168.