Fill in the five numbers 3, 4, 5, 6, and 7 into the box of the formula on the right, □*□□+□□=A, then what is the maximum value of A.
把3、4、5、6、7这五个数填入右边式子的方框里，□*□□+□□=A，则A最大等于多少．
<gadget id="calculator">7 * 64</gadget>
<output>448</output>

<gadget id="calculator">448 + 53</gadget>
<output>501</output>

<result>501</result>