A wire exactly winds a circle with a diameter of 4 decimeters 50 times. How long is the wire?
一根电线正好将一个直径是4分米的圆形绕满50圈，这根电线长多少米？
<gadget id="calculator">50 / 10</gadget>
<output>5</output>

<gadget id="calculator">3.14 * 4 * 5</gadget>
<output>62.8</output>

<result>62.8</result>