In □/7=523…□, what is the maximum number of the dividend.
在□/7=523…□中，被除数最大填多少．
<gadget id="calculator">523 * 7</gadget>
<output>3_661</output>

<gadget id="calculator">7 - 1</gadget>
<output>6</output>

<gadget id="calculator">3_661 + 6</gadget>
<output>3_667</output>

<result>3_667</result>