The sum of five consecutive odd numbers is 125, what is the smallest one among them?
五个连续奇数的和是125，其中最小的一个是多少．
<gadget id="calculator">125 / 5</gadget>
<output>25</output>

<gadget id="calculator">25 - 4</gadget>
<output>21</output>

<result>21</result>