The length of a cuboid container is 5 decimeters, the width is 4 decimeters, and the height of the water surface is 6 decimeters. Now put a cube of iron with a side length of 2 decimeters, how many decimeters will the water level rise at this time?
长方体容器的长是5分米、宽是4分米、水面高度6分米．现放入一块棱长为2分米的正方体铁块，这时水面升高多少分米？
<gadget id="calculator">5 * 4</gadget>
<output>20</output>

<gadget id="calculator">2 / 20</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">2 * 2 * (1/10)</gadget>
<output>2/5 = around 0.4</output>

<result>2/5 = around 0.4</result>