How many four-digit numbers can be formed with the six numbers 0, 1, 2, 3, 8, and 7 that are divisible by 9 without repeating numbers.
用0、1、2、3、8、7六个数字可以组成多少个能被9整除而又没有重复数字的四位数．
<gadget id="calculator">4 * 3 * 2 * 1</gadget>
<output>24</output>

<gadget id="calculator">3 * 3 * 2 * 1</gadget>
<output>18</output>

<gadget id="calculator">24 + 18</gadget>
<output>42</output>

<result>42</result>