Not in the U.S but in a lot of other countries. The benefits of not being local

Yes. Loud.

Kelly and Katy do.

Teenage Dream had 8

California Gurls #1
Teenage Dream #1
Firework #1
E.T. #1
Last Friday Night #1
The One That Got Away #3
Part of Me #1
Wide Awake #2

Yes, Beyoncé has 3 eras


Crazy in Love #1
Baby Boy #1
Naughty Girl
Me, Myself and I


Check On It #1
Deja Vu
Irreplaceable #1
Beautiful Liar


If I Were a Boy
Single Ladies #1
Halo
Sweet Dreams

Bonus:

Independent Women #1
Survivor
Bootylicious #1
Emotion

Yes, also she always put her LEAD singles at #1

'Christina Aguilera'
3 #1 singles.