In the product 1*2*3*...*498*499*500, how many zeros are there at the end?
在乘积1*2*3*…*498*499*500中，末尾有多少个零．
<gadget id="calculator">500 / 5</gadget>
<output>100</output>

<gadget id="calculator">500 / 25</gadget>
<output>20</output>

<gadget id="calculator">500 / 125</gadget>
<output>4</output>

<gadget id="calculator">100 + 20 + 4</gadget>
<output>124</output>

<result>124</result>