Beyoncé's "1+1" is a very strangely titled song—a vocal tour de force, with an indelible hook, that's named after a line we hear once, rather than the line that we hear again and again. "I don't know much about algebra," she sings, "but I know one plus one equals two." From an artist who's been nodding to classic soul her entire career (ever since Destiny's Child repeatedly evoked the Supremes), that's not a surprising line. It's a riff on Sam Cooke's 1960 hit "Wonderful World" ("Don't know much about algebra/Don't know what a slide rule is for/But I do know one and one is two..."), subsequently revived by Johnny Nash as a minor hit in 1976. (Terence Trent D'Arby recorded a well-loved version of "Wonderful World" in 1987, too, although his version oddly includes the altered lyrics from Art Garfunkel's 1977 cover.)

The rest of "1+1" plays with the diction of "Wonderful World," too, although it mostly switches over to military language: "I don't know much about guns... I don't know much about fighting." But the really memorable line of the song, the one Beyoncé keeps repeating, is "make love to me"—she lingers over every phoneme in that phrase, turning "love" into a two-syllable word. So why doesn't it have the more obvious title "Make Love to Me"?

Before Beyoncé recorded her version of "1+1," as it turns out, it was recorded by its co-writer The-Dream, and apparently initially intended to be the final track on his 2009 album Love vs. Money. He didn't call it either "1+1" or "Make Love to Me": his version was entitled "Nothing But Love"—again, a line that appears exactly once in the song (although "we ain't got nothing without love" is close)--but it's otherwise fairly similar, down to its "Purple Rain"-ish guitar solo. And yet Beyoncé changed its non-obvious title to another non-obvious title.

Maybe the problem is that "Make Love to Me" has been used as a title too many times before: the only earlier hit "One Plus One" (sic) was a math-themed, uptempo 1986 single by Force M.D.'s, who really knew how to rock sequined purple outfits. (Regular readers of this column may note with amusement that One Plus One was also the original title of Jean-Luc Godard's Rolling Stones film Sympathy for the Devil.)

The first "Make Love to Me" to make a splash as pop was a 1941 Artie Shaw foxtrot with vocals by Paula Kelly. The most important one, though, was Jo Stafford's 1954 #1 hit "Make Love to Me." (Ella Fitzgerald recorded that song too.) Unusually for the time, it had six co-writers—in those days, it was very rare for a song to have more than two or three contributors credited. (The reason is that it was based on an instrumental standard, initially recorded by the New Orleans Rhythm Kings in 1923 as "Tin Roof Blues"; the original group's members got credited, and so did the new lyricists.) Stafford's version has been revived a few times, most notably as a slinky funk duet by Johnny Thunder and Ruby Winters in 1967.

In 1978, Kelly Marie had an Australian hit single with a discofied song called "Make Love to Me"—no relation to any earlier one. It had no impact at all on the American charts, but the next year, the Australian-born singer Helen Reddy—who'd made at least as much of her career of being a voice of women's empowerment as Beyoncé has—recorded a cover of it with a slicker disco arrangement. Reddy's "Make Love to Me" hovered around the pop chart for a while, and was also her one and only R&B chart hit.

The only subsequent "Make Love to Me" to hit the charts has been Lorenzo's 1993 single "Make Love 2 Me." He's also the only male singer who's been able to make that demand on his own. (In pop, love is almost always made from a man to a woman: Boyz II Men sang "I'll Make Love to You," not the reverse.) That could be one of the reasons Beyoncé went for the mathematical title for The-Dream's song. Giving it the obvious title would suggest that it's only about longing to be on the receiving end of desire; calling it "1+1" emphasizes the idea that it's a song about dynamics within a partnership, and safety from the world outside.