There is a square iron block with a side length of 2 decimeters. Now it is forged into a cuboid. The cross section of this cuboid is a rectangle with a length of 4 cm and a width of 2 cm. Find its length.
有一块边长2分米的正方形铁块，现把它锻造成一根长方体，这个长方体的截面是一个长4厘米，宽2厘米的长方形，求它的长．
<gadget id="calculator">2 * 10</gadget>
<output>20</output>

<gadget id="calculator">4 * 2</gadget>
<output>8</output>

<gadget id="calculator">20 / 8</gadget>
<output>5/2 = around 2.5</output>

<gadget id="calculator">20 * 20 * (5/2)</gadget>
<output>1_000</output>

<result>1_000</result>