Britney Scores Fifth #1

Now listed as featured artist on "S&M," Spears earns her fifth Hot 100 No. 1 and second this year, following her own "Hold It Against Me" in January. She had previously reigned with her debut single "...Baby One More Time" in 1999 and returned to the summit with "Womanizer" (2008) and "3" (2009).

Source: Billboard