If the radius of the circle is increased from 3 cm to 5 cm, the area of the circle increases by how many square centimeters.
圆的半径由3厘米增加到5厘米，圆的面积增加了多少平方厘米．
<gadget id="calculator">5 ** 2</gadget>
<output>25</output>

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

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

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

<gadget id="calculator">78.5 - 28.26</gadget>
<output>50.24</output>

<result>50.24</result>