A rectangular steel block with a side length of 4dm is forged into a rectangular steel block with a width of 2.5dm and a height of 2dm. What is its length in dm?
把一个棱长4dm的正方体钢块，锻造成宽2.5dm，高2dm的长方体钢块，它的长是多少dm．
<gadget id="calculator">2.5 * 2</gadget>
<output>5</output>

<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">4 * 4 * (4/5)</gadget>
<output>64/5 = around 12.8</output>

<result>64/5 = around 12.8</result>