A person only remembers that his friend's phone number is 852309**, and he also remembers that the numbers are not repeated. If he wants to call his friend, how many times can he dial at most?
某人只记得友人的电话号码是852309**，还记得各数字不重复，要拨通友人的电话，这个人最多拨多少次．
<gadget id="calculator">4 * 3</gadget>
<output>12</output>

<result>12</result>