ABACUS – FRACTION ADDITION
I. GENERAL RULES :
a) Numerals such as 53 ,^107 etc., are known as fractions. In these fractions, the
numbers 3 and 7 are known as numerators and numbers 5 and 10 are denominators.
Numerals like^4 67 ,^543 etc., are known as complex fractions.b) Least Common Multiple : Consider two fractions, 54 and 97. Here 5 and 9 are the
denominators of the respective fractions. What is the common number into which
both the numbers 5 and 9 could be divided without leaving a remainder? 45, 90,
135 etc., are some common denominators. In addition and subtraction of fractions,
it is always suggested to use the smallest common denominator which is technically
known as the Least Common Multiple.
c) In addition and subtraction of fractions, the abacus is divided into three sections,
one for setting the whole number, the second for setting the numerator and the
third for setting the denominator.d) In fraction, the common denominator is set in the extreme right. Three columns -
the units, tens and hundreds columns are allotted for setting the denominator.
The fourth, fifth and sixth columns from the right side of the abacus are allotted
for setting the numerator. The seventh, eighth and ninth columns from the right
extreme of the abacus are allotted for setting the whole number. That is, the
numerator is set between the whole number and the denominator.
e) Please note that only three columns are allotted for the denominator. The same
procedure applies in the case of numerator and the whole number too. If your