The chord progression is fairly easy. I like to use a barred A-chord because it
makes a better sound with the song. This is my first tab and from just listening
to the song a couple times. I'm pretty sure I'm the first person to tab this song
too, so that's pretty cool.

Intro (Bruno Mars):
A (x02220@1)                      C#mI (x13321@4)wanna be a billionaire so fucking bad
F#m (244222@1)                         EBuy (022100@1)all of the things I never had
A (x02220@1)                        C#mI (x13321@4)wanna be on the cover of Forbes magazine
F#m (244222@1)                         ESmiling (022100@1)next to Oprah and the Queen
    F#m (244222@1)        E (022100@1)          AOh, (x02220@1)every time I close my eyes
  F#m (244222@1)          E (022100@1)           AI (x02220@1)see my name in shining lights
F#m (244222@1)       E (022100@1)        AA (x02220@1)different city every night
C#m  F#m  Bm
Oh   I-I  swear,
                    C#mThe (x13321@4)world better prepare
                         AFor (x02220@1)when I'm a billionaire

Verse 1 and 2 follow the same progression as the beginning A-C#m-F#m-E

3rd chorus is normal, but the 2nd chorus starts at "Oh every time I close my eyes..." 
has a little extra at the end of it where it just repeats billionaire. That little part is 
A-E

The end is just A-C#m

If you listen to the song, you'll get the idea of the strumming. Its reggae-esque and a 
catchy song. Hope this helps everyone!