Which ‘A’ is a calculating frame with sliding balls on wires?
Abacus Calculation Russian abacus Abaci Nepohualtzintzin Abacus (Aztec) Cranmer abacus Abacuses Counting frame Abacus Abacist Abacus (mathematics) Abacists Bead frame Abacus arithmetic AbacuS Counting frames Abbacus Reckoning frame