Cut a largest square from a circle with a diameter of 8 cm, find the area of the square.
在一个直径为8厘米的圆形里剪一个最大的正方形，求正方形的面积．
<gadget id="calculator">8 / 2</gadget>
<output>4</output>

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

<gadget id="calculator">8 * 2 * 2</gadget>
<output>32</output>

<result>32</result>