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e) With the help of your left hand, clear one bead in the tens column. That is, you
have cleared 10 instead of 9.
f) To compensate this excess in clearing, add one bead in the units column
(i.e., add one bead with the already available two beads). The answer is 63.

C. Example : 378 - 179


a) Set the number 378 in the extreme right. That is, set the number 3 of the 378
in the hundreds column, 7 in the tens column and 8 in the units column.
b) In the given example, we have to subtract 1 in the hundreds column, 7 in the
tens column and 9 in the units column.
c) Clear one bead in the hundreds column. You have 2 beads left now.
d) Clear 7 in the tens column (left hand follows the right and rests on 2 in the
hundreds column). You have no beads left now in the tens column.
e) Move both hands to the right to clear 9 in the units column. It is not possible
because you have only 8 in the units column.
f) Move your hands to clear one bead in the tens column. Incidentally, there is no
bead left in the tens column. This is typical, isn’t it? Now move your hands to
the left. Clear one bead in the hundreds column. This means you have cleared
100 instead of clearing 9.
g) What is the complement number of 9 with respect to 100? It is 91. This
number must be added to compensate the excess. That is, add 9 beads in the
tens column and one bead in the units column. In the tens column, there is
no bead. So your addition results as 0+9=9. In the units column, you have
the value 8 and to this value, 1 bead is added making it 9. Thus you get the
answer as 199.
EXERCISE


  1. 984 – 234

  2. 842 – 599

  3. 1024 – 55

  4. 10889 – 7024

  5. 5904 – 4801


6. 8324 – 524


7. 105711 – 4305


8. 232824 – 99821


9. 172844 – 81234


10. 334781 – 70024

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