Each entry of an ARPA table for a modeled language includes an n-gram Az, an associated backoff value Az.p equal to the conditional probability p(z|A) that symbol z follows context A in the modeled language, and an associated backoff weight value Az.b for the context A. A method comprises: (1) computing and adding for each entry of the ARPA table in descending n-gram order an associated maximum backoff weight product value Az.m; (2) after performing operation (1), computing and adding for each entry of the ARPA table in descending n-gram order an associated max-backoff value Az.w=maxh p(z|hA) which is the maximum backoff value for any head h preceding the context A of the n-gram Az; and (3) extending the ARPA table by adding a column storing the associated maximum backoff weight product values Az.m and a column storing the associated max-backoff values Az.w.