China

Chinese mathematical history dates back three thousand years or more. Around 220 BC, the ancient Chinese built the Great Wall, which was a major triumph of engineering skill and mathematical calculation.
The Chinese may have been the first to develop a decimal place-value system, similar to the one we use today. For their calculations they used a form of counting board, a box with separate compartments for units, tens, hundreds, etc., into which small bamboo rods were placed. Most ancient Chinese mathematics was written on bamboo strips which perished with time; those shown here record a 9 × 9 multiplication table. Various Chinese measuring instruments have survived, including a distance-measuring drum cart from around AD 300 and a 1437 armillary sphere, an astronomical device for representing the great circles of the heavens. The abacus has appeared in different forms around the world, originally as a sand tray with pebbles; the Chinese version consists of a frame with beads, called a ‘suan pan’.
[China 1953, 2012; Liberia 1999; Togo]