Subtract 5 from a number, multiply by 5, add 5, divide by 5, and the final result is still 5, so what is this number?
一个数减去5，乘以5，加上5，除以5，最后的结果还是5，那么这个数是多少？
<gadget id="calculator">5 * 5</gadget>
<output>25</output>

<gadget id="calculator">25 - 5</gadget>
<output>20</output>

<gadget id="calculator">20 / 5</gadget>
<output>4</output>

<gadget id="calculator">4 + 5</gadget>
<output>9</output>

<result>9</result>