If the side length of a square is 126 decimeters, what is its perimeter in centimeters?
一个正方形的边长是126分米，它的周长是多少厘米．
<gadget id="calculator">126 * 4</gadget>
<output>504</output>

<gadget id="calculator">504 * 10</gadget>
<output>5_040</output>

<result>5_040</result>