Final answer:
In Parliamentary Procedure, the proper name for the number of members needed to legally transact business is called a Quorum.
Step-by-step explanation:
In Parliamentary Procedure, the proper name for the number of members needed to legally transact business is called a Quorum. A quorum is the minimum number of members that must be present in order for the legislative body to conduct official business and make decisions. It is usually defined as a majority of members, which means more than half of the total number of members.