MIAMI — The Cereal Bowl, a cafe concept offering customers the chance to mix and match breakfast cereals, has opened its first location in Washington, D.C. The company, which operates stores in Newark, Del., and New Brunswick, N.J., hopes to have 10 stores opened by the end of 2010, including one in Education City, Qatar. Founded in 2004, The Cereal Bowl previously operated a store in Coral Gables, Fla., but that location closed in 2008.