There are four cards, each with a number written on the front and back. The first card has 0 and 1, the second card has 2 and 3, the third card has 5 and 6, and the fourth card has 7 and 8. Take two out of these four cards and put them in a row, so how many different two-digit numbers can be formed in total. (Note: 6 on the card can be placed into 9.)
有四张卡片，正、反面各写有1个数字．第一张写有0和1，第二张写有2和3，第三张写有5和6，第四张写有7和8．从这四张卡片中取出两张，放成一排，那么一共可以组成多少个不同的两位数．(注意：卡片上的6可以摆成9．)
<gadget id="calculator">5 * 7</gadget>
<output>35</output>

<gadget id="calculator">3 * 6</gadget>
<output>18</output>

<gadget id="calculator">35 + 18</gadget>
<output>53</output>

<result>53</result>