cuboid glass container, the bottom of which is a square with a side length of 2 decimeters, pour 5 liters of water into the container, and then put a watermelon into the water. At this time, the height of the water surface is 2 decimeters. What is the volume of this small watermelon? ?
一个长方体玻璃容器，底面是边长2分米的正方形，向容器中倒进5升的水，再把一个西瓜放进水中，这时水面高度是2分米，这个小西瓜的体积是多少？
<gadget id="calculator">2 * 2</gadget>
<output>4</output>

<gadget id="calculator">5 / 4</gadget>
<output>5/4 = around 1.25</output>

<gadget id="calculator">2 - (5/4)</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">2 * 2 * (3/4)</gadget>
<output>3</output>

<result>3</result>