Area of each tile = 18in x 18 in = 1.5 ft * 1.5 ft = 2.25 sq ft.
Number of tiles required = 670/2.25 = 297.77... tiles, that is a minimum of 298 tiles.
That is the mathematical answer. It assumes that the shape to be covered is "well-behaved", that almost all offcuts are used and that there is almost no wastage. In real life all three assumptions are unrealistic and you should make an allowance of 5-7% - more if you are not an expert.
266.666666666 so rounding up 267 tiles.
67 tiles.
10
100 tiles or 96 which is the correct amount
288
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.
288
118