3 (Britney Spears song)

"3" is a song recorded by American singer Britney Spears. It is from her second greatest-hits album, "The Singles Collection". "3" was released to American radio on September 29, 2009. It is about a threesome, with a hook that references the music group Peter, Paul and Mary. It was written by Max Martin, Shellback, and Tiffany Amber, while Martin and Shellback produced it.
The song entered at #1 on the "Billboard" Hot 100 and also reached the top of the charts in Canada. It reached the top ten in Australia, the UK, Belgium (Wallonia), Finland, Sweden, and Norway.
As of 2016, "3" has sold over 2.4 million copies in the US alone.