suanpan

thumb|Suanpan (the number represented in the picture is 6,302,715,408) thumb|Chinese Abacus thumb|upright=1.35|right|An extended version of a suanpan thumb|right|upright=1.35|A modern 4+1 suanpan (soroban) with a clear-all button thumb|upright=1.35|Suanpan- reincarnation of counting rods The suanpan (), also spelled suan pan or souanpan) is an abacus of Chinese origin. The earliest known written documentation of the Chinese abacus dates to the 2nd century BCE during the Han dynasty, and it was later described in a 190 CE book of the Eastern Han dynasty, namely Supplementary Notes on the Art of Figures written by Xu Yue. However, the exact design of this suanpan is not known. Usually, a suanpan is about 20 cm (8 in) tall and it comes in various widths depending on the application. It usually has more than seven rods. There are two beads on each rod in the upper deck and five beads on each rod in the bottom deck. The beads are usually rounded and made of a hardwood. The beads are counted by moving them up or down towards the beam. The suanpan can be reset to the starting position instantly by a quick jerk around the horizontal axis to spin all the beads away from the horizontal beam at the center.

Suanpans can be used for functions other than counting. Unlike the simple counting board used in elementary schools, very efficient suanpan techniques have been developed to do multiplication, division, addition, subtraction, square root and cube root operations at high speed.