A cube has 6 sides.
A cube is all made up of squares.
So, we need to find the area of one cube and multiply that by 6.
Length * width= area
40*40= 1,600
Multiply that by 6.
1,600*6= 9600
Whatever the unit is after that: in, feet, cm, m, etc- put that after the number with ^2.
9,600 (the unit) ^2
I hope this helps!
~kaikers