Select 6 consecutive natural numbers from 1 to 999 so that there are exactly 4 0s at the end of their product. How many ways are there in total?
从1～999中选出连续6个自然数，使得它们的乘积的末尾恰有4个0，一共有多少种选法．
<gadget id="calculator">12 + 5</gadget>
<output>17</output>

<result>17</result>