If a square has a perimeter of 28 meters, what is the area in square meters?
一个正方形，周长是28米，面积是多少平方米．
<gadget id="calculator">28 / 4</gadget>
<output>7</output>

<gadget id="calculator">7 * 7</gadget>
<output>49</output>

<result>49</result>