I have to respond to a few other poster's comments on this topic, because my other thread (U2 & The Floyd) was closed...conveniently..."rolling eyes"...
The RIAA didn't start counting double albums as two units sold instead of one until 1997. And therefore only Echoes..., The Wall Live 1980-'81: Is There Anybody Out There?, Delicate Sound Of Thunder and the latest certification of The Wall in 1999 for 23x Platinum (11.5 Million copies) would be deducted from Floyd's album sales total, which currently stands at 73.5 Million in the US. So, even though you'd have to deduct the four albums mentioned above accordingly, you'd have to ad these certifications (because of the amount these albums sell annually and considering the last time these albums had been certified) below because they've already hit these sales levels - it's just that they haven't been certified by the RIAA yet:
The Dark Side Of The Moon - 18x Platinum
The Wall - 25x Platinum (12.5 Million copies)
Wish You Were Here - 7x Platinum
Animals - 5x Platinum
Delicate Sound Of Thunder - 4x Platinum (2 Million copies)
Pulse - 4x Platinum (2 Million copies)
Atom Heart Mother - Platinum
Pink Floyd's US album sales total is at least 66 Million.
Oh and U2 also have a couple of albums that are counted as two unit sales instead of one (big surprise no one brought that up). In case you haven't guessed what they are, they are The Best Of: '80-'90 (B-Sides) & The Best Of: '90-'00 (B-Sides). So, you'd have to deduct 2 or 3 Million from U2's RIAA US total, then ad HTDAAB for 2x Platinum (2.4 Million sold in the US to date, not 3x Platinum) and The Joshua Tree for 11x Platinum, since it sells around 100,000 annually in the US. Bringing U2's US total to over 50 Million units sold in the US to date.