A cement pipe has an outer diameter of 1.6 meters and an inner diameter of 1 meter. What is the area of the cross-section of this cement pipe in square meters?
一种水泥管，外圆直径是1.6米，内圆直径是1米．这根水泥管横截面的面积是多少平方米？
<gadget id="calculator">1.6 / 2</gadget>
<output>0.8</output>

<gadget id="calculator">0.8 ** 2</gadget>
<output>0.64</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">0.64 - (1/4)</gadget>
<output>0.39</output>

<gadget id="calculator">3.14 * 0.39</gadget>
<output>1.2246</output>

<result>1.2246</result>