Last year, 342 fry were stocked, and the number of fry this year is twice that of last year. How many tails are stocking 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．今年放养多少尾？
<gadget id="calculator">342 * 2</gadget>
<output>684</output>

<result>684</result>