Basic models usually have thirteen rods, but the number of rods on practical or standard models often increases to 21, 23, 27 or even 31, thus allowing calculation of more digits or representations of several different numbers at the same time.
Modelele de bază au de obicei 13 coloane, dar numărul de coloane al unui model practic sau standard de obicei ajunge la 21, 23, 27 sau chiar 31, permițând astfel calcule cu numere cu mai multe cifre, sau reprezentarea simultană a mai multor numere.