The perimeter of a square is 12 cm. Draw a largest circle inside the square. What is the circumference of this circle in cm?
正方形的周长是12厘米，在正方形里面画一个最大的圆，这个圆的周长是多少厘米．
<gadget id="calculator">12 / 4</gadget>
<output>3</output>

<gadget id="calculator">3.14 * 3</gadget>
<output>9.42</output>

<result>9.42</result>