Agreement mismatches in number, gender or case present an interesting challenge to any grammatical theory. We consider two styles of analysis for a number mismatch in Welsh, which arises when nouns are modified by cardinal numbers. In this construction, the nominal must be singular. One analysis pursues the idea that the nominal is an argument of the numeral, with some elements agreeing with the numeral and some with the noun. The other adopts the distinction between INDEX and CONCORD features (King and Dalrymple 2004), together with the proposal that in this construction it is the numeral which determines the plurality of the INDEX.