How many feet of wallpaper border paper do you need so you can put a border around the ceiling of a room if the room's dimensions are 10 10 9 and 1over2 feet and 8 and 1over2 feet?

Answer 1

To put up wallpaper as a border, you do not need area. You just need the 2 lengths and 2 widths (separate because not all walls are even in every room). *You do not need the area of the room.
You have the wall measurements of:
10 feet
10 feet
9 and 1/2 feet and
8 and 1/2 feet

You would just add those up.

However, it is always best when doing DIY home projects to buy a little extra to cover for mistakes in measuring or cutting. Or for doing a small repair if the paper gets marred in the future. So, I would ignore the 1/2 measurements and round those up, so your measurement would be:
10 feet
10 feet
10 feet (rounded up) and
9 feet rounded up
Add those up for the total feet you will need.

In the empty room, re-measure each wall's length. Lay out the paper and measure,giving yourself 1/8th inch extra on ONE end of EACH piece; using pencil on the backside of the paper make a light pencil mark like this: |

The excess 1/8th can be hidden or cut off if unneeded.

After you apply each piece, going in order around the room, write in pencil on the back of the left-over piece any name this design has, then put it into a plastic bag to keep in clean and put it on a shelf in that room's closet. If you want or need to buy more later, you will have the name and an example of its pattern/colors.