In the formula □/△=5...7, how much is the minimum filling of □
在算式□/△=5…7中，□最小填多少
<gadget id="calculator">7 + 1</gadget>
<output>8</output>

<gadget id="calculator">8 * 5</gadget>
<output>40</output>

<gadget id="calculator">40 + 7</gadget>
<output>47</output>

<result>47</result>