A 28 cm long wire is used to form a square, what is the area of the square in square centimeters?
用一根28厘米长的铁丝围成一个正方形，这个正方形的面积是多少平方厘米．
<gadget id="calculator">28 / 4</gadget>
<output>7</output>

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

<result>49</result>