Abacus is a device used for calculations and has been in use for centuries. It can be used for mathematical operations such as, addition, subtraction, multiplication, division, roots (square and cube), etc. It is used as a teaching aid in schools and blind children also make use of it to carry out large multiplication and long division. There are different types of abacus that have been used in different countries.
In general, an abacus has beads that slide over rods. A Chinese abacus has two rows of beads, one of which has two beads each and symbolizes digit '5', while the other set of rows have 7 beads each (each corresponding to 1). To represent '11', we will choose 2 beads from '5's and one bead from '1s'.
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