There is a circle whose radius is 6cm, if its radius increases by 1cm, how much does its area increase in cm**2.
有一个圆半径是6cm，如果它的半径增加1cm，它的面积增加多少cm**2．
<gadget id="calculator">6 + 1</gadget>
<output>7</output>

<gadget id="calculator">7 ** 2</gadget>
<output>49</output>

<gadget id="calculator">6 ** 2</gadget>
<output>36</output>

<gadget id="calculator">49 - 36</gadget>
<output>13</output>

<gadget id="calculator">3.14 * 13</gadget>
<output>40.82</output>

<result>40.82</result>