If the diameter of a circle increases from 2 cm to 6 cm, its area increases by how many square centimeters.
一个圆的直径从2厘米增加到6厘米，它的面积增加了多少平方厘米．
<gadget id="calculator">6 / 2</gadget>
<output>3</output>

<gadget id="calculator">3 ** 2</gadget>
<output>9</output>

<gadget id="calculator">3.14 * 9</gadget>
<output>28.26</output>

<gadget id="calculator">2 / 2</gadget>
<output>1</output>

<gadget id="calculator">1 ** 2</gadget>
<output>1</output>

<gadget id="calculator">3.14 * 1</gadget>
<output>3.14</output>

<gadget id="calculator">28.26 - 3.14</gadget>
<output>25.12</output>

<result>25.12</result>