There are 6 number cards with 3, 4, 5, 6, 7, and 8 written on them. Draw two out of them, how many odd numbers are there among all the two-digit numbers formed?
有6张数字卡片，分别写着3、4、5、6、7、8．从中抽出两张，组成的所有的两位数中，奇数有多少个．
<gadget id="calculator">5 * 3</gadget>
<output>15</output>

<result>15</result>