A four-digit number, each digit is different, and all of them are not 0, if the sum of these four numbers is 12, how many such four-digit numbers are there?
一个四位数，各位数字互不相同，且都不为0，若这四个数字之和是12，则这样的四位数有多少个．
<gadget id="calculator">4 * 3 * 2 * 1</gadget>
<output>24</output>

<gadget id="calculator">24 + 24</gadget>
<output>48</output>

<result>48</result>