The subject of this study is the analysis of one of the structural elements of constitutional concepts: the statutory number of deputies, the statutory number of senators and the statutory number of members of the National Assembly. The authors consider, among others, the issue of the legitimacy of calculating the constitutional majority, quorum, as well as the required number of signatures, from the total number of members, instead of the actual number. They separate a temporary and permanent reduction in the number of parliamentarians, analyzing their impact on parliamentary practice. In conclusion, they share the generally accepted interpretation of the concept of the statutory number of members, according to which it is always the composition specified in law, regardless of the actual composition, even in the situation where the law itself sanctions such a reduction, but pointing to the legitimacy of using this concept in constructing some constitutional majority and bypassing it in other cases.