An iron hoop is placed on the periphery of a circular wooden barrel. The outer diameter of the barrel is 50 cm, and an iron bar of 6 cm is needed at the joint of the iron hoop. How many centimeters of iron bars are needed to make such a hoop.
一个圆形木桶的外围打一个铁箍，桶外直径是50厘米，铁箍连接处需要铁条6厘米．打这样的一个铁箍需要铁条多少厘米．
<gadget id="calculator">3.14 * 50</gadget>
<output>157</output>

<gadget id="calculator">157 + 6</gadget>
<output>163</output>

<result>163</result>