How to calculate the room area of 5 meters long, 3 meters wide and 2.4 meters high

How to calculate the room area of 5 meters long, 3 meters wide and 2.4 meters high

Surface area:
(5 × 3 + 5 × 2.4 + 3 × 2.4) × 2 = 68.4 (M2)
Volume:
5 × 3 × 2.4 = 36 (M3)