Three-five-zero-zero.

Ripped open by metal explosion
Caught in barbed wire; fireball, bullet shock
Bayonet, electricity, shrapnel, throbbing meat
Electronic data processing
Black uniforms, bare feet, carbines
Mail order rifles shoot the muscles
256 Viet Cong captured...
256 Viet Cong captured...

(first time whispered)

Prisoners in N***ertown
It's a dirty little war
Three-five-zero-zero
Take weapons up and begin to kill
Watch the long long armies drifting home...

http://cmhair.monblogue.branchez-vous.com/

But, interestingly enough, that may not be what the song "Three-Five-Zero-Zero" in Hair refers to. Jim Rado has said that the song was inspired by an Alan Ginsberg’s poem. Ginsberg’s "Wichita Vortex Sutra," written in February 1966, contains almost all the freaky, violent, surrealistic images in the song "Three-Five-Zero-Zero," often quoted word-for-word. In the poem, General Maxwell Taylor proudly reports to the press that three thousand, five hundred of the enemy were killed in one month. He repeats the number, digit by digit, for effect: "Three-Five-Zero-Zero." In addition to the many other images from the poem that found their way into the song, Ginsberg also refers to 256 Vietcong killed and 31 captured, which became 256 captured in the song lyric. Though the song starts out somber and intense, spilling out Ginsberg’s images of death and dying, it turns midway into a manic dance number, an absurdist celebration of killing that echoes Maxwell’s glee at reporting the enemy casualties, commenting on the Happy Face that the U.S. government tried to put on the ever diminishing returns of the war in Vietnam. While our soldiers (and theirs) kept dying, Washington tried to whip up World War II-style support for the war among Americans. But we had seen the war on our TV screens this time, and we weren’t celebrating.

http://www.orlok.com/hair/holding/articles/HairArticles/scottmiller.html