There is a square flower bed on the field with a side length of 13 meters. If the flower bed is surrounded by a guardrail of 9 yuan per meter, how much will it cost?
场上有一个正方形花坛，边长为13米，如果用每米9元的护栏把花坛围上，需要多少钱？
<gadget id="calculator">13 * 4 * 9</gadget>
<output>468</output>

<result>468</result>