a room is 31feet by15feet and i am putting 12inch by 12inch tiles how many tiles do i need
74 of them. Get 80 to be safe.
It is necessary to know the area of the kitchen An area is measured in square feet and no such information is provided in the question.
If the floor tiles are measured in inches and the room is measured in feet then the tiles are 1sq feet and the room is 6x8 = 48 sq feet so you would need 48 tiles.
675 of them. Get extra for breakage.
205.3125 tiles exactly OR 206 tiles, with a bit left over!
To cover 720 sq feet of floor with 18" x 18" tile, you would need 320 tiles.
240 square tiles are needed
1.5 tiles. (I know it's unusual, but it's true.)