rectangular iron sheet with a length of 32 centimeters is cut off at its four top corners to form a square with a side length of 4 centimeters, and then folded and welded to form a rectangular parallelepiped iron box without a cover. It is known that the volume of this tin box is 768 cubic centimeters. What is the area of the original sheet of iron?
一块长方形铁皮，长32厘米，在它四个顶角分别剪去边长4厘米的正方形，然后折起来焊成一个无盖的长方体铁皮盒．已知这个铁皮盒的容积是768立方厘米．原来这块铁皮的面积是多少？
<gadget id="calculator">4 * 2</gadget>
<output>8</output>

<gadget id="calculator">32 - 8</gadget>
<output>24</output>

<gadget id="calculator">24 * 4</gadget>
<output>96</output>

<gadget id="calculator">768 / 96</gadget>
<output>8</output>

<gadget id="calculator">8 + 4 + 4</gadget>
<output>16</output>

<gadget id="calculator">32 * 16</gadget>
<output>512</output>

<result>512</result>