The diameter of a circular fish pond is 20m. If an average of 15 fish fry are placed per square meter of water surface, how many fish fry should be placed in this fish pond?
一个圆形养鱼池的直径是20m，如果平均每平方米水面投放鱼苗15尾，那么这个养鱼池一共要投放鱼苗多少尾？
<gadget id="calculator">20 / 2</gadget>
<output>10</output>

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

<gadget id="calculator">3.14 * 100 * 15</gadget>
<output>4_710</output>

<result>4_710</result>