In a glass tank with a length of 40dm and a width of 20dm filled with water, a square iron block with a side length of 10dm is placed. The iron block is completely submerged in the water and the water does not overflow. How many centimeters does the water level rise?
在一个长40dm，宽20dm装着水的玻璃缸中，放入一块棱长为10dm的正方形铁块，铁块全部浸没在水中，并且水未溢出，这时水面升高了几厘米？
<gadget id="calculator">40 * 20</gadget>
<output>800</output>

<gadget id="calculator">10 / 800</gadget>
<output>1/80 = around 0.0125</output>

<gadget id="calculator">10 * 10 * (1/80) * 10</gadget>
<output>25/2 = around 12.5</output>

<result>25/2 = around 12.5</result>