If the pool feet its a 76

If each tile is a 6 feet how many tiles
I need

if the pool is 76 feet long

and each tile is 6 feet you need 13 tiles because 12 tiles only goes 72 feet

However do you not need other rows of tile? This is a very strange question. Most tiles are about 6 inches, not six feet and they are square and you have to fit them in areas, not lengths. I think you have the question wrong.