CNN News Clip

Jack had not been to San Francisco before, and he was looking forward to seeing Fisherman's Wharf, North Beach, Nob Hill, Chinatown, and the Civic Center. However, the first thing he wanted to do was look up his old friend, Charlie, who lives on Main Street in San Francisco. He bought a map and looked up Charlie's street in the index. It was listed as (7, B). What does (7, B) mean?

In mathematics, such a representation is called an ordered pair and has many useful applications. The first one we'll consider in this section is called a Cartesian coordinate system and sets the stage for the remainder of this chapter.