Exes Demi Lovato and Joe Jonas teamed up for a few 'Camp Rock' classics at kick-off of the Jonas Brothers' 20th anniversary tour on Sunday (Aug. 10).

In The Number Ones, I’m reviewing every single #1 single in the history of the Billboard Hot 100, starting with the chart’s beginning, in 1958, and working my way up into the present. Book Bonus Beat: ...