How Many Gallons Of Paint Would Cover 118 Square Footage?

This site tells what square footage to expect from a gallon of paint. It depends on the surface, and whether it is interior or exterior paint. For most smooth surfaces, it is 400 ft² or more for the first coat.

Assuming you have 118 ft² of interior gypsum board surface, it will take about
  118 ft²/(400 ft²/gal) = 118/400 gal = .295 gal
That's a little bit less than 2 1/2 pints of paint.

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If you had a room 11 ft by 10 ft with an 8 ft ceiling, and you wanted to paint the walls, the total surface area would be
  area = height*perimeter = (8 ft)(2(11 ft + 10 ft)) = 16(21) ft² = 336 ft²
It would take about (336/400) gal = 0.84 gal to paint the walls of that room.