ABACUS - ADDITION
I. GENERAL RULES :
a) Finger position is very important in operating the abacus. The fingers should
not ‘butterfly’ over it. The thumb should operate ONLY the lower abacus and the
index finger should operate the upper abacus. On any account, the positions
should not be changed.
b) Take this example : 48 + 67
Here, the number 48 should be set in the extreme right of the abacus - the
number 8 in the units column and 4 in the tens column.
If you need the number 67 also in the abacus for remembering, set it in the left
extreme of the abacus. There is no hard and fast rule for setting this number in
the particular column in the left side of the abacus. This is just for REFERENCE.
c) One of the important aspects to remember in abacus is the position of the two
hands on that. The left index finger and the right index finger should always be
placed on the consecutive columns for avoiding confusion. The placement of
the hands should be emphasised very much while teaching the visually disabled
child. Otherwise, children will miss track of the problem.
d) In the addition of numbers, the digit in the units column of the first number
should be added with the corresponding digit of the second number. Similarly
the corresponding digits of the numbers must be added. On any account, the
units column of the first number and the tens column of the second number
should not be added. This procedure is just like the addition techniques followed
by sighted children. However a small difference is noted. In normal addition,