The base of a parallelogram is 9 decimeters, and the height is twice the base, what is its area?
一个平行四边形的底是9分米，高是底的2倍，它的面积是多少．
<gadget id="calculator">9 * 2</gadget>
<output>18</output>

<gadget id="calculator">9 * 18</gadget>
<output>162</output>

<result>162</result>