So, if I multiply 1.5 times the length of each strip that will give me the area of each strip. If I multiply that number by 143 squares, that gives me the total area needed for each color. So, for example, for strip 3, I mulitplied 1.5 x 2.5 x 143 = 536.25 sq in. If 3/8 of a yard of fabric (13.5 x 43 inches wide) has 580.5 sq in, I should need 3/8 yd for strip 3. Is my math correct on this? If this is true, I'll end up buying 13.33 yards of fabric. If so, then I think I've figured this out. Hopefully my 8 years of teaching middle school math is correct.