If the length of the rectangle is increased by 3 times and the width is increased by 4 times, how many times will the area of the rectangle be increased?
把长方形的长扩大3倍，宽扩大4倍，这个长方形的面积扩大多少倍．
<gadget id="calculator">3 * 4</gadget>
<output>12</output>

<result>12</result>