How many 18 inch tiles are needed for 28'x13' room?

Answer 1

I'm assuming you meant foot and a half on each side of your square tiles.

18' / 1.5' = 12 tiles across that way...

13' / 1.5' = 8 2/3 tiles down that way...

if this was a real construction project, you'd buy 12x9 tiles, or 108 tiles, and throw away the little sections you had to cut off.

if this was a math problem, (maybe putting the little cut sections together to make more tiles?) 12 x 8 2/3 = 104 tiles, with no leftover little sections remaining : )