After unfolding the sides of a cylinder, a rectangle with a length of 21 cm and a width of 15 cm is obtained. What is the maximum possible volume of this cylinder? (π takes an approximate value of 3)
把一个圆柱的侧面展开后得到一个长21厘米、宽15厘米的长方形，这个圆柱的体积最大可能是多少？(π取近似值3)
<gadget id="calculator">21 / 3 / 2</gadget>
<output>7/2 = around 3.5</output>

<gadget id="calculator">(7/2) ** 2</gadget>
<output>49/4 = around 12.25</output>

<gadget id="calculator">3 * (49/4) * 15</gadget>
<output>2_205/4 = around 551.25</output>

<result>2_205/4 = around 551.25</result>