Mom wants to change two cylindrical pillows with a height of 40cm and a diameter of 20cm into a cylindrical pillow with a height of 60cm and a diameter of 20cm. How many square centimeters of cloth are left? (cloth for seams is ignored)
妈妈要把两个高是40cm，底面直径是20cm的圆柱形布抱枕改为一个高60cm，底面直径是20cm的圆柱形靠枕，剩下多少平方厘米布？(接缝用布忽略不计)
<gadget id="calculator">3.14 * 20 * 40</gadget>
<output>2_512</output>

<gadget id="calculator">20 / 2</gadget>
<output>10</output>

<gadget id="calculator">10 ** 2</gadget>
<output>100</output>

<gadget id="calculator">3.14 * 100</gadget>
<output>314</output>

<gadget id="calculator">2_512 + 314 + 314</gadget>
<output>3_140</output>

<gadget id="calculator">3_140 * 2</gadget>
<output>6_280</output>

<gadget id="calculator">3.14 * 20 * 60</gadget>
<output>3_768</output>

<gadget id="calculator">3_768 - 628</gadget>
<output>3_140</output>

<gadget id="calculator">6_280 - 3_140</gadget>
<output>3_140</output>

<result>3_140</result>