100! =1*2*3*...*99*100, how many 0s are there at the end of this product?
100！=1*2*3*…*99*100，这个乘积的结尾共有多少个0．
<gadget id="calculator">100 / 5</gadget>
<output>20</output>

<gadget id="calculator">100 / 25</gadget>
<output>4</output>

<gadget id="calculator">20 + 4</gadget>
<output>24</output>

<result>24</result>