Cut out a small square from each of the four corners of a rectangular cardboard with a length of 40cm and a width of 30cm to make a rectangular parallelepiped carton with a depth of 5cm. What is its volume? (neglected at joints)
将一个长40cm，宽30cm的长方形硬纸板的四角各剪去一个小正方形，做一个深5cm的长方体无盖纸盒，它的容积是多少？(接头处忽略不计)
<gadget id="calculator">5 * 2</gadget>
<output>10</output>

<gadget id="calculator">40 - 10</gadget>
<output>30</output>

<gadget id="calculator">30 - 10</gadget>
<output>20</output>

<gadget id="calculator">30 * 20 * 5</gadget>
<output>3_000</output>

<result>3_000</result>