The outer diameter of a circular iron sheet is 12 cm, and the inner diameter is one-third of the outer diameter. What is the area of this iron sheet?
一块环形铁皮的外直径是12厘米，内直径是外直径的三分之一，这块铁皮的面积是多少？
<gadget id="calculator">12 / 2</gadget>
<output>6</output>

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

<gadget id="calculator">3.14 * 36</gadget>
<output>113.04</output>

<gadget id="calculator">12 / 3</gadget>
<output>4</output>

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

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

<gadget id="calculator">3.14 * 4</gadget>
<output>12.56</output>

<gadget id="calculator">113.04 - 12.56</gadget>
<output>100.48</output>

<result>100.48</result>