It is controversial whether a classifier (C) or measure word (M) in Chinese forms a constituent first with Num (numeral) or N in a [Num C/M N] phrase. This paper reviews evidence for the [Num C/M] constituency from modern Chinese and then provides evidence from historical and typological perspectives. Under the [Num C/M] constituency, not only the C/M word orders attested in Chinese history, but also all those attested elsewhere, can be straightforwardly accounted for by the head parameter, while such simplicity is unattainable under the [C/M N] constituency. In addition, fresh evidence is obtained from the internal word order within a complex numeral; e.g. san-shi '30' is base-final, with n (3) and base (10) entering into a multiplicative function, 3x10. The same multiplicative function exists between Num and C/M, e.g. san-duo hua '3 C flower' = 3x1 flower, and san-da hua '3 dozen flower' = 3x12 flower. C/M and bases are thus unified as multiplicands, an insight further supported by the consistent correlation between the base-final order and the C/M-final order throughout the history of Chinese. A closer examination of the 103 classifier languages in Greenberg (1990) further reveals that, among the 52 languages whose numeral systems and C/M word orders can be obtained, the synchronization between the numeral base and C/M is nearly universal. The base-C/M unification as multiplicands and base-C/M synchronization in word order strongly suggest that Num and C/M form a single constituent.