"Billionaire" by Travie McCoy featuring Bruno Mars tops the 3 million mark this week. The song hit #4 in June 2010. It's Mars' third 3-million seller, following his own "Just The Way You Are" and "Grenade." It's McCoy's first. "Cupid's Chokehold," his biggest hit with Gym Class Heroes, has sold 1,918,000 copies.