Cut out the largest circle from a square with a side length of 4 cm, what is the remaining area in cm**2.
从一个边长是4cm的正方形里剪下一个最大的圆，剩下的面积是多少cm**2．
<gadget id="calculator">4 * 4</gadget>
<output>16</output>

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

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

<gadget id="calculator">3.14 * 4</gadget>
<output>12.56</output>

<gadget id="calculator">16 - 12.56</gadget>
<output>3.44</output>

<result>3.44</result>