The total length of connected blood vessels in the human body is 2.5 times that of the earth's equator, which is about 40,000 kilometers long. The human body is distributed with large and small blood vessels. Do you know the total length of human blood vessels is tens of thousands of kilometers?
人体中血管连接起来的总长度是地球赤道的2.5倍，赤道长约4万千米．人体分布着大大小小的血管．你知道人体血管的总长度是多少万千米吗？
<gadget id="calculator">4 * 2.5</gadget>
<output>10</output>

<result>10</result>