A cylindrical paint bucket has a base diameter of 15 cm and a height of 20 cm. What is the minimum square centimeter of iron sheet required to make a pair of such paint buckets?
一种圆柱形油漆桶，底面直径是15厘米，高是20厘米．做一对这样的油漆桶至少需要铁皮多少平方厘米？
<gadget id="calculator">3.14 * 15 * 20</gadget>
<output>942</output>

<gadget id="calculator">15 / 2</gadget>
<output>15/2 = around 7.5</output>

<gadget id="calculator">(15/2) ** 2</gadget>
<output>225/4 = around 56.25</output>

<gadget id="calculator">3.14 * (225/4) * 2</gadget>
<output>353.25</output>

<gadget id="calculator">942 + 353.25</gadget>
<output>1_295.25</output>

<gadget id="calculator">1_295.25 * 2</gadget>
<output>2_590.5</output>

<result>2_590.5</result>