Naughty uses a 20 cm long rope to form the largest square. What is the side length of this square in cm?
淘气用20厘米长的绳子围成一个最大的正方形，这个正方形的边长是多少厘米．
<gadget id="calculator">20 / 4</gadget>
<output>5</output>

<result>5</result>