If we take the total number of accepted BBs, 152,532, observe that every one of the 53 used reaction essentially follows the pattern A + B  C, we can calculate the theoretically possible maximum number of products as a ½ * 153,532 2 * 53 ~ 617 billion. (We ignore, for simplicity's sake, the possibility that in some cases, when multiple reactive groups are present in a BB, one could have A + B  C and B + A  C'. We remove such cases anyway during the reactant pair generation.) Our actually generated product set being 1.75 billion, our success rate in this sense is about 1/350. This reduction is caused by both (a) the fact that most pairs R1 and R2 do not match the PATRAN patterns of any of our transforms, and (b) the 51% loss rate encountered by KILL statements in the CHMTRN reaction logic.