An abacus, pl. abaci, is an institution that trains mathematicians, producing indexers, calculator, and clerks. They study the numerical systems that make up the cosmos and live a monastic life, but are rigorously trained. The abaci consider themselves the true heirs of the Phlegms' mathematical study and are rivals of the newer athenaeums.
The abacus (plural abaci or abacuses), also called a counting frame, is a calculating tool that was in use centuries before the adoption of the written modern numeral system and is still widely used by merchants, traders and clerks in Asia, Africa, and elsewhere.