A cuboid iron box with a square bottom, if its sides are unfolded, a square with a side length of 24 cm can be obtained. If there is half a tank of water in the iron box, find the area of the surface in contact with the water.
底面是正方形的长方体铁箱，如果把它的侧面展开正好得到一个边长是24厘米的正方形．若铁箱内装有半箱水，求与水接触的面的面积．
<gadget id="calculator">36 + 576</gadget>
<output>612</output>

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

<gadget id="calculator">612 * (1/2)</gadget>
<output>306</output>

<result>306</result>