How many different four-digit numbers can be formed with two 1s, one 2, and one 3?
用两个1，一个2，一个3，可以组成多少个不同的四位数？
<gadget id="calculator">4 / 2</gadget>
<output>2</output>

<gadget id="calculator">3 * 2 * 2 * 1</gadget>
<output>12</output>

<result>12</result>