a, b, and c are three different natural numbers, and a+b+c=18, what is the maximum value of a*b*c
a、b、c是三个不同自然数，且a+b+c=18，则a*b*c最大值为多少
<gadget id="calculator">5 * 6 * 7</gadget>
<output>210</output>

<result>210</result>