The radius of a circle is 5 cm, if the radius increases by 5 cm, how much does the area increase?
一个圆的半径是5厘米，如果半径增加5厘米，则面积增加多少．
<gadget id="calculator">5 + 5</gadget>
<output>10</output>

<gadget id="calculator">10 ** 2</gadget>
<output>100</output>

<gadget id="calculator">3.14 * 100</gadget>
<output>314</output>

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

<gadget id="calculator">3.14 * 25</gadget>
<output>78.5</output>

<gadget id="calculator">314 - 78.5</gadget>
<output>235.5</output>

<result>235.5</result>