Add a number a to the left of 724 and a number b to the right to form a five-digit number. If the five-digit number is a multiple of 6, what is the maximum value of the product of A and B?
在724的左边添一个数字a，右边添加一个数字b，组成一个五位数．如果这个五位数是6的倍数，那么A与B积的最大值等于多少．
<gadget id="calculator">8 * 9</gadget>
<output>72</output>

<result>72</result>