<Ul> <Li> file </Li> <Li> help </Li> </Ul> <P> "25 or 6 to 4" is a song written by the American musician Robert Lamm, one of the founding members of the band Chicago . It was recorded in 1969 for their second album, Chicago, with Peter Cetera on lead vocals . The album was released in January 1970 and the song was edited and released as a single in June of that same year, climbing to No. 4 on the U.S. Billboard Hot 100 chart and number seven on the UK Singles Chart . It was the band's first song to reach the top five in the U.S. It has been included in numerous Chicago compilation albums . </P> <P> An updated version of "25 or 6 to 4" was recorded for the 1986 album Chicago 18 with James Pankow listed as co-writer . With the new band member Jason Scheff on lead vocals, the single reached No. 48 on the U.S. chart . This version was also used as the B - side for the band's next single in 1986, "Will You Still Love Me?". </P> <P> Through the 2010s, "25 or 6 to 4" continued to be a staple in Chicago's live concert set list, and in Peter Cetera's solo concert set list . In 2016, former drummer, Danny Seraphine, reunited on stage with Chicago to perform "25 or 6 to 4" and two other songs at their induction ceremony for the Rock and Roll Hall of Fame . </P>

Who sang lead vocals on 25 or 6 to 4