A factory car uses 4.2 tons of gasoline per month, how many tons of gasoline are used by 3 such factory cars in a quarter.
一辆厂车每月用汽油4.2吨，3辆这样的厂车一个季度用油多少吨．
<gadget id="calculator">4.2 * 3 * 3</gadget>
<output>37.8</output>

<result>37.8</result>