144/(1.5*1.5) = 64 tiles, but if you are using this to determine how many are needed to tile a room, you need to add at least 10% for edging around the room. So, you probably need at least 71 or more tiles.
The answer depends on the measurement units used for 18x18.
22.2 tiles so buy 23 tiles.
266.666666666 so rounding up 267 tiles.
192 tiles
67 tiles.
start with 38 tiles.
220
10
100 tiles or 96 which is the correct amount
102.22 tiles because each tile is 2.25 sq.ft. 230 / 2.25 =102.22 so really 103 tiles.
118
288