A classroom is 8.4 meters long and 2.1 times its width. What is the size of this classroom in square meters?
一间教室长8.4米，是宽的2.1倍．这间教室的面积是多少平方米？
<gadget id="calculator">8.4 / 2.1</gadget>
<output>4</output>

<gadget id="calculator">8.4 * 4</gadget>
<output>33.6</output>

<result>33.6</result>