Last year, 342 fish fry were stocked. This year, the number of fish fry stocked this year is twice that of last year. How many fish are stocked this year?
去年放养鱼苗342尾，今年放养的鱼苗尾数是去年的2倍，今年放养了多少尾．
<gadget id="calculator">342 * 2</gadget>
<output>684</output>

<result>684</result>