An earthquake can be felt as far as 100 kilometers away from the epicenter. How big is the area that can be felt?
一次地震，最远离震中100千米的地方都有震感，有震感的面积有多大？
<gadget id="calculator">100 ** 2</gadget>
<output>10_000</output>

<gadget id="calculator">3.14 * 10_000</gadget>
<output>31_400</output>

<result>31_400</result>