Choose any two of the four cards with 2, 4, 6, and 8 written on them respectively to form a two-digit number. If its "6" can be regarded as "9", how many different two-digit numbers are there?
从分别写有2，4，6，8的四张卡片中任取两张，组成一个两位数．如果其"6"可以看做"9"，那么共有多少种不同的两位数？
<gadget id="calculator">4 + 4 + 3 + 4 + 3</gadget>
<output>18</output>

<result>18</result>