A three-digit number □65, when the number is filled in □, it is a multiple of 9.
一个三位数□65，□里填多少时，是9的倍数．
<gadget id="calculator">2 * 9</gadget>
<output>18</output>

<gadget id="calculator">6 + 5</gadget>
<output>11</output>

<gadget id="calculator">18 - 11</gadget>
<output>7</output>

<result>7</result>