The diameter of the large circle of a ring is 6cm, and the radius of the small circle is 2cm. What is the area of the ring in cm**2.
一个圆环的大圆的直径是6cm，小圆半径是2cm，这个圆环的面积是多少cm**2．
<gadget id="calculator">6 / 2</gadget>
<output>3</output>

<gadget id="calculator">3 ** 2</gadget>
<output>9</output>

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

<gadget id="calculator">9 - 4</gadget>
<output>5</output>

<gadget id="calculator">3.14 * 5</gadget>
<output>15.7</output>

<result>15.7</result>