How do i find surface area of a box?

Question

How do i answer this question?:
15 by 18 by 20
Please tell me the formula!! AND QUICK!!!!!!!!!!

Answer 1

add the surface areas of the sides (they're all rectangles, so it'll be basexheight)

15*18+
15*18+
15*20+
15*20+
18*20+
18*20=1860 un. square
or
2(15*18)+
2(15*20)+
2(18*20)=1860 un. square

and if is an open box, don't count that side. for example, if the top of the box is 18 x 20, and it is open, the formula would be:
15*18+
15*18+
15*20+
15*20+
18*20=1500 un. square
or
2(15*18)+
2(15*20)+
1(18*20)=1500 un. square

Answer 2

The box is abviously a cuboid. It can be defined as a 3D rectangle.

The formula for surface area is:
2(lb + bh + hl)

where l is length, b is breadth and h is the height
Here, l = 15, b = 18, h = 20
Applying the formula mentioned above:

Surface area = 2[(15*18) + (18*20) + (15*20)]
= 2(270 + 360 + 300)
= 2 * 930
= 1860 sq. units

Answer 3

..15 x 20 x 2 = 600
..15 x 18 x 2 = 540
..20 x 18 x 2 = 720

..600 + 540 + 720 = 1860 units²

Answer 4

The total surface area of a cuboid is given by the formula
=2(length*breadth+
breadth*height+length*
height)
=2(15*18+18*20+15*20)
=2(270+360+300)
=2*930
=1860 sq. units
(Please note that it does not matter which side you take as length,breadth or height)

Answer 5

2(15*18)+ 2(15*20)+2(18*20)=540+600+720
=1860 unit square