RITD was the big nominated song, so she sang it .
It was no promo in mind there really. Besides, SFTTR already got its 2 weeks on top w/o any promo whatsoever
1. Part Of Me - Katy Perry (Canada) (=)
1. Part Of Me - Katy Perry (USA) (=)
1. Part Of Me - Katy Perry (New Zealand) (=)
3. Part Of Me - Katy Perry (Australia) (=)
25. Part Of Me - Katy Perry (Spain) (-6)
25. Part Of Me - Katy Perry (France) (=)
32. Part Of Me - Katy Perry (Italy) (=)
32. Part Of Me - Katy Perry (Sweden) (+9)
45. Part Of Me - Katy Perry (Norway) (+10)
48. Part Of Me - Katy Perry (Germany) (+5)
65. Part Of Me - Katy Perry (Finland) (-6)
80. Part Of Me - Katy Perry (Belgium) (+3)
108. Part Of Me - Katy Perry (Nederlands) (-16)
111. Part Of Me - Katy Perry (Denmark) (+4)
They should've discounted it a few weeks ago while it was hot on radio.
She is starting to lose 1 mil on radio everyday, so idk how well she can hold on for Billboard Hot 100 because the tracking week for radio ends on Wednesday...
I can't believe how well Selena is holding up. I also can't believe how high One Direction has gone I love Starships<3 and i'm happy Part of Me is #1. I want Kelly to go higher tho.
I am also shocked by One Direction but happy for them.
I said the same thing, and others responded saying RITD was a better choice since it's essentially her signature song and it served as a full circle moment, which I can agree with.
Didn't get SFTTR back to #1, but judging by HDD's Billboard 200 predictions, it was the right move.
.
And people say Katy and Adele dislike each other. 
I love Starships<3 and i'm happy Part of Me is #1. I want Kelly to go higher tho.
I just noted this!