A cuboid packaging box is 20 cm long, 4 cm wide, and 8 cm high. If this box is used to form a cube, what is the minimum length of the sides of the cube?
一种长方体包装盒，长20厘米，宽4厘米，高8厘米，如果用这种盒子垒成一个正方体，这个正方体的棱长至少是多少厘米．
<gadget id="calculator">2 * 2 * 5 * 2</gadget>
<output>40</output>

<result>40</result>