Why are the beads on the abacus usually two above and five below?

Now only five beads are used, because the decimal system is used now. China used hexadecimal in ancient times, and the hexadecimal design was 2*5+5= 15. In addition, "half a catty and eight taels" is a hexadecimal counting method.

Because in ancient China, the numeration system was 16, not 10, which we commonly use now. Therefore, in the 16 system, one of the upper two beads represents five, two beads are combined, and one of the lower five beads represents one, and five beads are combined, which adds up to exactly 15, so it's time to add files.

Abacus, also known as abacus and abacus, is a simple calculation tool invented by our ancestors. The abacus calculation originated in the Northern Song Dynasty, and it was not counted until the Northern Song Dynasty. Abacus is a simple calculation tool invented and created by the working people in ancient China.

China is the hometown of abacus. Today, computers have been widely used. The ancient abacus has not been abandoned, but it is in the ascendant in many countries because of its convenience and accuracy.

Therefore, people often associate the invention of abacus with? Four great inventions of ancient china, a famous painting in the Northern Song Dynasty? There is an abacus in Zhao Taicheng's medicine cabinet on the riverside at Qingming Festival. Because of its convenient and quick operation, abacus has been widely used by working people in ancient China for thousands of years. Even the most advanced modern electronic calculator can't completely replace the abacus.

UNESCO was just here? Through Baku, the capital of Azerbaijan, abacus officially became the intangible cultural heritage of mankind. This is also the 30th non-legacy project in China.