premise: While the particular limits of these groupings may seem artificially arbitrary ; they do fairly express a corresponding grouping of more variable material , and they eventuate also in five classes , along a similar scale , containing approximately equal numbers of cases , namely 19 , 14 , <mask> , 11 , 12 in Athabascan .
hypothesis: the proper context for <mask> here should be the cardinal number that is the sum of fourteen and one