Insert a rectangular cuboid wooden stick with a square bottom and a 10cm bottom side vertically into a square cuboid container with a side length of 40cm. At this time, the water depth is 80cm. When the stick is lifted to a distance of 30 cm from the bottom, what is the length in cm of the part of the water that the stick lifts out of?
底面边长为40cm的正方形的长方体容器中，垂直插入底面为正方形、底边长是10cm的长方体木棒，这时水深80cm．当小棒提到离底面30cm处时，小棒提出水面部分的长度是多少cm．
<gadget id="calculator">10 * 10 * 30</gadget>
<output>3_000</output>

<gadget id="calculator">40 * 40</gadget>
<output>1_600</output>

<gadget id="calculator">10 * 10</gadget>
<output>100</output>

<gadget id="calculator">1_600 - 100</gadget>
<output>1_500</output>

<gadget id="calculator">3_000 / 1_500</gadget>
<output>2</output>

<gadget id="calculator">30 + 2</gadget>
<output>32</output>

<result>32</result>