140 Mm Times 120 Mm Times 4 Mm. What Is The Surface Area Of This Jewel Case?

Surface area is length times width,,
so I'm guessing that the 4mm is depth, not needed
140 x 120 = 16800mm squared ( surface area)

if its volume you are after
then
140 x 120 x 4 = 67200mm cubed ( volume )