A rectangular piece of land is 10 meters long and 6 meters wide. If the length and width are doubled, how many square meters will the area increase?
一块长方形地长10米，宽6米，如果长和宽都扩大2倍，那么面积增加了多少平方米？
<gadget id="calculator">10 * 2</gadget>
<output>20</output>

<gadget id="calculator">6 * 2</gadget>
<output>12</output>

<gadget id="calculator">20 * 12</gadget>
<output>240</output>

<gadget id="calculator">10 * 6</gadget>
<output>60</output>

<gadget id="calculator">240 - 60</gadget>
<output>180</output>

<result>180</result>