The inner diameter of a disc is 2 cm and the outer diameter is 12 cm. What is the area of the disc in square centimeters?
一张光盘内圆直径是2厘米，外圆直径是12厘米，这张光盘的面积是多少平方厘米．
<gadget id="calculator">12 / 2</gadget>
<output>6</output>

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

<gadget id="calculator">2 / 2</gadget>
<output>1</output>

<gadget id="calculator">1 ** 2</gadget>
<output>1</output>

<gadget id="calculator">36 - 1</gadget>
<output>35</output>

<gadget id="calculator">3.14 * 35</gadget>
<output>109.9</output>

<result>109.9</result>