Singer is also set to collaborate and pen songs for other artists
The track will appear on 'The Hunger Games: Catching Fire' soundtrack
The chart-topping singer wrote a blog post around her 17th birthday
The rapper adds new verses to the Number One song
Meanwhile, Katy Perry bags second UK Number One with 'Prism'
Rapper also praises Miley Cyrus, calling the twerking pop singer a 'really clever girl'
Pop singer's US Number One hit finally became available to download in the UK at midnight today (October 20)
'Royals' star keen to pen hits for other artists, including a K-Pop girlband
16 year old singer says she is surprised nobody else wrote something similar before she got the chance