ABACUS – FRACTION SUBTRACTION
a) The procedures followed in fraction addition are to be followed in fraction subtraction
also. Here, the numerator and the whole number of the second fraction should be
subtracted from the corresponding numerator and the whole number of the first fraction.
b) Consider the example :^9 85 −^61211.
c) Set the whole number, numerator and the denominator of the first fraction in the
respective columns.
d) See the denominators of the two fractions. They are 8 and 12. What is the lowest
common denominator of these two? It is 24. Now set the common denominator in the
right extreme of the abacus.
e) Subtract the whole number of the second fraction from the whole number of the first
fraction. That is 9–6=3. You are left with 3 in the whole number column.
f) Now take the first fraction. It is 85. Set the numerator 5 in the extreme left of the
abacus; skip one column and set the denominator 8. By keeping your left hand on the
8 and right hand on the common denominator 24, ask : how many 8’s in 24? By saying
3, clear the eight and set 3. Now multiply 3 and the numerator 5. By saying 15, set
the 15 in the numerator column. That is, set the 1 in the fifth column and 5 in the
fourth column respectively. Clear the first fraction which has been set in the extreme
left of the abacus.
Module – 19
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