.33 it takes 3 bundles to cover a square. A square is 10'x10'
http://wiki.answers.com/Q/How_many_square_in_a_bun...

Before you start your project, you need to calculate the size of the roof you intend to cover. The square footage of a roof is normally measured in "squares" of 100 feet
http://www.ehow.com/way_5580726_manysquarefeetb...

Three bundles of shingles make a "square". A square of shingles sho...
http://www.chacha.com/question/howmanybundlesof...

It depends on the shingle, but there are 3 bundles in 100 square feet, and 22 shingles in a bundle.
http://www.kgbanswers.com/howmanysquarerinab...
