since 12"X12" is inches, we convert that to feet meaning 1'X1'
238 sq feet of floor is the same as 238 tiles at 1 sq ft each.
I assume that the 12 before 12X12 in your question is how many tiles in a box. You will need to divide 238 by the number of tiles per box.
So 238/12 is how you get the to the final answer; 19.8 boxes. We round UP to the next nearest box to cover breakages and funny cuts.
13 boxes with 13 tiles in each
256 tiles
100
5.3 obviosly
144
13 boxes with 13 tiles in each
80 if the tiles are 12x12 - 12x12 is one square foot covering 80 you would need 80 tiles
256 tiles
100
5.3 obviosly
68
14
144
1540
650
168
Well if 12x12 is one square foot and you have 44 you need to cover figure 10% for breakage (5 tiles) it looks like 50 tiles will do ya