If the radius of a circle with a circumference of 20 decimeters is increased by 5 times, what is the circumference in decimeters?
将一个周长为20分米的圆的半径扩大为原来的5倍，则周长变为多少分米．
<gadget id="calculator">20 * 5</gadget>
<output>100</output>

<result>100</result>