Use 3, 5, 7, and 9 to arrange four digits that do not repeat, so that it is a multiple of 5. How many different arrangements are there?
用3，5，7，9排成不重复的四位数，使它是5的倍数，共有多少种不同的排法．
<gadget id="calculator">3 * 2 * 1 * 1</gadget>
<output>6</output>

<result>6</result>