The radius of a circular flower bed is 3m. If the radius of this flower bed is increased by 1m, the area will be increased by how much m**2.
一个圆形花坛的半径是3m，如果将这个花坛的半径增加1m，面积就会增加多少m**2．
<gadget id="calculator">3 + 1</gadget>
<output>4</output>

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

<gadget id="calculator">3.14 * 16</gadget>
<output>50.24</output>

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

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

<gadget id="calculator">50.24 - 28.26</gadget>
<output>21.98</output>

<result>21.98</result>