It's numbered 5: Guardians. The math is all screwed up because all of a sudden we're introducing a ton of variables to solve for, and just solving for G alone is going to be a bitch. I think 343 is just making up numbers and throwing everything they have at the wall praying that things stick. Hence the Beta this far in advance and praying they have enough time to change the entire math formula if it blows up in their face.