Question

Find the area of cardboard required to make an open cubical box of side 40cm

Answer 1

First we will take out the area of one cardboard (square) = side ×side
= 40×40=160cm^2
Now as we know there are six faces of cubes but since the box is open then we will take only 5 sides so total area of cardboard required = area of one cardboard × 5
= 160×5
=800 cm^2

Answer 2

the area of cardboard should be 160 so  its side will be 40