Cut the largest circle out of a square with a side length of 1 cm, (take 3 for π) what is the area of this circle.
在边长为1厘米的正方形上剪下一个最大的圆，(π取3)这个圆的面积是多少．
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">(1/2) ** 2</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">3 * (1/4)</gadget>
<output>3/4 = around 0.75</output>

<result>3/4 = around 0.75</result>