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The abacus was invented several thousand years ago. There was nobody around to take a picture of the inventors. The forerunner of the camera was invented less than 200 years ago.
China invented the abacus .
The Abacus
The abacus was invented to help people calculate.
addition subtraction multiplication and division
the Chinese invented the abacus
abacus was not invented by chinese, but by babylonians.
Abacus's advantage is improving mental calculations whereas its size and weight are its disadvantages.
abacus the Chinese invented it
The abacus was invented by the Sumerians in 2,700 BCE, not in 1642 ACE
The abacus was invented before cameras and so no photograph exists.
China invented the Abacus.