If the length and width of a rectangle are both increased by 10%, what is the increase in the area of the new rectangle compared to the original rectangle?
一个长方形的长与宽都增加10%后，新长方形的面积与原来的长方形相比较，面积增加了多少
<gadget id="calculator">1.21 - 1</gadget>
<output>0.21</output>

<result>0.21</result>