A rectangular piece of paper is 10 cm long and 7 cm wide. If you want to cut out the largest square, what is the perimeter of the square in cm?
一张长方形纸长10厘米，宽7厘米，如果要剪下一个最大的正方形，正方形的周长是多少厘米．
<gadget id="calculator">7 * 4</gadget>
<output>28</output>

<result>28</result>