rope can just form a rectangle with a length of 80 cm and a width of 40 cm. If it is used to form a square, find the area of the square.
一根绳子，正好能围成一个长80厘米、宽40厘米的长方形，如果用它围成一个正方形，求正方形的面积．
<gadget id="calculator">80 + 40</gadget>
<output>120</output>

<gadget id="calculator">2 / 4</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">120 * (1/2)</gadget>
<output>60</output>

<gadget id="calculator">60 * 60</gadget>
<output>3_600</output>

<result>3_600</result>