18 in = 1.5 ft
area of one tile, 18inx18in, =1.5ftx1.5ft= 2.25 ft2 /tile
432ft2/2.25ft2 /tile=192 tiles
But probably when you come to the wall you will have to cut a row of tiles to fit, so you will need extras.
How many extra tiles would depend on the actual dimensions of the room.
Suggestion; draw the plan of the room to scale and draw in lines to show the tiles. Then you can count them.
area of one tile, 18inx18in, =1.5ftx1.5ft= 2.25 ft2 /tile
432ft2/2.25ft2 /tile=192 tiles
But probably when you come to the wall you will have to cut a row of tiles to fit, so you will need extras.
How many extra tiles would depend on the actual dimensions of the room.
Suggestion; draw the plan of the room to scale and draw in lines to show the tiles. Then you can count them.