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.
Pricing Asphalt Shingles. The average cost to install an asphalt shingle roof is anywhere between $1,700 and $8,400 depending on the slope, pitch and size of your roof. The material cost factors into that price, and as such shingle prices vary depending on your location and the specific product. Materials: In addition to purchasing the shingle squares, you will need roofing felt, which averages $18 per roll. 2  Attaching all of the materials requires a roofing nail gun using a standard roll of 1 1/4 galvanized nails at $65 each and roofing cement, which costs approximately $22 per gallon.