This is the thirteenth video in the series of lessons on math provided by DeafTEC. Gary Blatto-Vallee, a math and science instructor at the National Technical Institute for the Deaf, guides viewers through a variety of mathematical exercises in this DeafTEC video series. All lessons are fully captioned, signed in ASL, and voiced. In this 7:46 video, Blatto-Vallee uses an electronic whiteboard to show several examples of finding the greatest common factor of two monomials. See the Math Video Resources page on DeafTEC's website for an introduction to this video series.