A ring-shaped gasket of a machine part has an outer diameter of 4 cm and an inner diameter of 1 cm. What is the area of the gasket?
一个环形的机器零件垫片，外直径4厘米，内直径1厘米，这个垫片的面积是多少？
<gadget id="calculator">4 / 2</gadget>
<output>2</output>

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

<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">(1/2) ** 2</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">4 - (1/4)</gadget>
<output>15/4 = around 3.75</output>

<gadget id="calculator">3.14 * (15/4)</gadget>
<output>11.775</output>

<result>11.775</result>