When a number is divided by 18, the quotient has a remainder of 27. What is the maximum number that can be.
一个数除以18，商27有余数，这个数最大可以是多少．
<gadget id="calculator">27 * 18</gadget>
<output>486</output>

<gadget id="calculator">18 - 1</gadget>
<output>17</output>

<gadget id="calculator">486 + 17</gadget>
<output>503</output>

<result>503</result>