Dad put a rockery rock in a cuboid fish tank with a bottom area of 56 square decimeters. The rockery rock was completely immersed in the water, and the water surface rose by 4 cm. How big is the rockery rock?
爸爸在一个底面积为56平方分米的长方体鱼缸里放了一个假山石，假山石完全浸入水中，水面上升了4厘米，这个假山石的体积有多大？
<gadget id="calculator">4 / 10</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">56 * (2/5)</gadget>
<output>112/5 = around 22.4</output>

<result>112/5 = around 22.4</result>