If the length of an arc is (5/8) of the circumference and the radius is 4 cm, what is the length of the arc?
若一弧长为圆周长的(5/8)，半径为4厘米，则弧长为多少．
<gadget id="calculator">2 * 3.14 * 4</gadget>
<output>25.12</output>

<gadget id="calculator">5 / 8</gadget>
<output>5/8 = around 0.625</output>

<gadget id="calculator">25.12 * (5/8)</gadget>
<output>15.7</output>

<result>15.7</result>