There are 1, 2, 3, 4, four number cards, how many different three-digit numbers can be formed by drawing three of them.
有1，2，3，4，四张数卡，从中抽取三张，能组成多少个不同的三位数．
<gadget id="calculator">4 * 3 * 2</gadget>
<output>24</output>

<result>24</result>