Have you ever wondered what makes one pop song a hit and another a flop? The answer isn't money, reports NPR’s All Things Considered, which calculated the cost of writing, producing, and marketing "Man Down," a track from Rihanna’s latest CD, Loud. It’s currently bringing up the rear on iTunes Top 100 Songs Chart, but that's not for lack of money spent: To come up with the songs for the album, Def Jam held a writing camp in March 2010, putting the best music writers in the best studios in LA for about two weeks. Producers play lyric-less tracks, and the songwriters write ("Man Down" took 12 minutes to pen). Rihanna ultimately picks her favorites. Renting the 10-or-so studios probably cost $200,000, or about $18,000 a song. The songwriter walked away with $15,000 for the tune; the producer grabbed $20,000. Def Jam paid another $10,000 to $15,000 to the vocal producer who coaches Rihanna in the studio, and the same amount for mixing and mastering the song. That's $78,000. But then the real money comes in. An industry expert estimates Def Jam spent about $1 million to make sure the song is everywhere. "You want them to turn on the radio and hear Rihanna, turn on BET and see Rihanna, walk down the street and see a poster of Rihanna, look on Billboard, the iTunes chart, I want you to see Rihanna first. All of that costs." And Rihanna doesn't make any money til Def Jam recoups its costs.