Correct Answer : abacus
The earliest calculating devices is Abacus.
There is a long history detailing the invention of computing and calculating machines. The earliest recorded calculating device is the abacus. Used as a simple computing device for performing arithmetic, the abacus most likely appeared first in Babylonia (now Iraq) over 5000 years ago.
Uses by the blind. An adapted abacus, invented by Tim Cranmer, called a Cranmer abacus is still commonly used by individuals who are blind. A piece of soft fabric or rubber is placed behind the beads so that they do not move inadvertently.
May not answer this directly, but Tim Cranmer invented the Cranmer abacus. The oldest surviving counting board is the Salamis tablet (originally thought to be a gaming board), used by the Babylonians circa 300 B.C., discovered in 1846 on the island of Salamis.
