Their purpose is to implement Boolean Logic. You might notice the correspondence to Binary Semantics and thus Binary (number system) logic & mathematics. Special fun: OR and XOR (exclusive OR).
Geographical Considerations: While most contractors will price their asphalt shingles roof replacement services within $4.00 to to $7.00 per square foot or $400 to $700 per square range, there will be significant geographic variations.
How much an asphalt shingle roof should cost. Average costs and comments from CostHelper's team of professional journalists and community of users. Do-it-yourself materials run around $680-$3,700 for a typical one-story ranch-style home with a 1,700-2,100-square-foot, gently-sloping roof.