The width of a rectangle is 8 cm and the length is twice the width. What is its area in square centimetres.
一个长方形的宽是8厘米，长是宽的2倍．它的面积是多少平方厘米．
<gadget id="calculator">8 * 2 * 8</gadget>
<output>128</output>

<result>128</result>