Take three numbers randomly from the four numbers 0, 1, 2, and 3 to form a three-digit number. How many different three-digit numbers can be formed in total?
从0、1、2、3四个数字中任意取出三个数字，组成一个三位数，一共可以组成多少个不同的三位数．
<gadget id="calculator">3 * 3 * 2</gadget>
<output>18</output>

<result>18</result>