After a number is enlarged by 1000 times, then it is reduced by 10 times to get 0.4. What is the original number?
一个数扩大1000倍后，再缩小10倍得0.4，原来这个数是多少．
<gadget id="calculator">0.4 / 100</gadget>
<output>0.004</output>

<result>0.004</result>