The area of a rectangle is 50 square centimeters, if its length and width are doubled, what is the area?
一个长方形的面积是50平方厘米，如果把它的长和宽都扩大3倍，面积是多少．
<gadget id="calculator">3 * 3</gadget>
<output>9</output>

<gadget id="calculator">50 * 9</gadget>
<output>450</output>

<result>450</result>