mostly addition & subtraction. you can do multiplication & division to but they are about an order of magnitude more difficult. even more complicated calculations can be done, if you learn how, but they rapidly become prohibitively difficult to do.
China invented the abacus .
ABACUS
disadvantage of abacus
How did the abacus occur?
An Abacus has beads and strings.
The Chinese abacus
the history about the abacus is that 3000 years ago the chinese invented the abacus. The abacus was made of wood parrelel rod and beads.
it is the abacus. :D :D :D i got is dummies
The abacus II!
the Chinese invented the abacus
the invenor of the abacus is the invenor of me
Abacus was invented by the Chinesethe abacus was also known as the first computer