What is the area of a square surrounded by a wire 28 cm long?
用一根长28厘米的铁丝围成一个正方形，这个正方形的面积是多少？
<gadget id="calculator">28 / 4</gadget>
<output>7</output>

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

<result>49</result>