Dad put a rockery rock in a cuboid fish tank with a bottom area of 45 square decimeters, and the water surface rose by 3 centimeters. How big is this rockery?
爸爸在一个底面积是45平方分米的长方体鱼缸中放了一个假山石，水面上升了3厘米．这个假山石的体积有多大？
<gadget id="calculator">3 / 10</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">45 * (3/10)</gadget>
<output>27/2 = around 13.5</output>

<result>27/2 = around 13.5</result>