One volleyball can be exchanged for 3 badmintons, one badminton can be exchanged for two table tennis balls, and one volleyball can be exchanged for how many table tennis balls.
1个排球可换3个羽毛球，一个羽毛球可换2个乒乓球，1个排球可换多少个乒乓球．
<gadget id="calculator">2 * 3</gadget>
<output>6</output>

<result>6</result>