Decimal Abacus 1000PV303 Posted on February 23, 2017November 4, 2020 by admin This wooden base abacus with measure 15 cm x 4 cm, thickness 18 mm having 7 holes with 7 spikes of 4 mm thick metal, provided with 70 beads of 7 colors. This abacus gives the facility to understand decimal place value.