The perimeter of a circular playground is 400m. If a colored flag is inserted every 20m along the circle, how many colored flags should be inserted in total.
一个环形操场的周长是400m，如果沿着一圈每隔20m插一面彩旗，一共需要插多少面彩旗．
<gadget id="calculator">400 / 20</gadget>
<output>20</output>

<result>20</result>