There is a ring-shaped part with an inner diameter of 80 cm and an outer diameter of 120 cm. Draw it on the plan at a scale of 1:40. What is the area of the ring on the graph?
有一个圆环形零件，内直径是80厘米，外直径是120厘米，按1：40的比便尺画在平面图上，求图上环形的面积是多少？
<gadget id="calculator">1 / 40</gadget>
<output>1/40 = around 0.025</output>

<gadget id="calculator">80 * (1/40)</gadget>
<output>2</output>

<gadget id="calculator">(1/40) / 2</gadget>
<output>1/80 = around 0.0125</output>

<gadget id="calculator">120 * (1/80)</gadget>
<output>3/2 = around 1.5</output>

<gadget id="calculator">(3/2) ** 2</gadget>
<output>9/4 = around 2.25</output>

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

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

<gadget id="calculator">(9/4) - 1</gadget>
<output>5/4 = around 1.25</output>

<gadget id="calculator">3.14 * (5/4)</gadget>
<output>3.925</output>

<result>3.925</result>