The diameter of a circle is 8 cm, if the diameter of the circle increases by 2 cm, how much does the area of the circle increase in square centimeters?
一个圆的直径是8cm，如果这个圆的直径增加2cm，那么这个圆的面积增加多少平方厘米．
<gadget id="calculator">8 + 2</gadget>
<output>10</output>

<gadget id="calculator">10 / 2</gadget>
<output>5</output>

<gadget id="calculator">5 ** 2</gadget>
<output>25</output>

<gadget id="calculator">8 / 2</gadget>
<output>4</output>

<gadget id="calculator">4 ** 2</gadget>
<output>16</output>

<gadget id="calculator">25 - 16</gadget>
<output>9</output>

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

<result>28.26</result>