i.e.,, 0.005( 5 times, 0 remainder )
Step. 3 : Divide 5 by 2
i.e.,, 0.0512 ( 2 times, 1 remainder )
Step. 4 : Divide 12 i.e.,, 12 by
2
i.e.,, 0.0526 ( 6 times, No remainder )
Step. 5 : Divide 6 by 2
i.e.,, 0.05263 ( 3 times, No remainder )
Step. 6 : Divide 3 by 2
i.e.,, 0.0526311(1 time, 1 remainder )
Step. 7 : Divide 11 i.e.,, 11 by 2
i.e.,, 0.05263115 (5 times, 1
remainder )
Step. 8 : Divide 15 i.e.,, 15 by 2
i.e.,, 0.052631517 ( 7 times, 1
remainder )
Step. 9 : Divide 17 i.e.,, 17 by 2
i.e.,, 0.05263157 18 (8 times, 1
remainder )
Step. 10 : Divide 18 i.e.,, 18 by 2
i.e.,, 0.0526315789 (9 times, No remainder )
Step. 11 : Divide 9 by 2
i.e.,, 0.0526315789 14 (4 times, 1
remainder )
Step. 12 : Divide 14 i.e.,, 14 by 2
i.e.,, 0.052631578947 ( 7 times, No remainder )
Step. 13 : Divide 7 by 2
i.e.,, 0.05263157894713 ( 3 times,
1 remainder )
Step. 14 : Divide 13
i.e.,, 13 by 2
i.e.,, 0.052631578947316 ( 6
times, 1 remainder )
Step. 15 : Divide 16 i.e.,, 16 by 2
i.e.,, 0.052631578947368 (8 times, No remainder
)
Step. 16 : Divide 8 by 2
i.e.,, 0.0526315789473684 ( 4 times, No remainder
)
Step. 17 : Divide 4 by 2
i.e.,, 0.05263157894736842 ( 2 times, No
remainder )
Step. 18 : Divide 2 by 2
i.e.,, 0.052631578947368421 ( 1 time, No
remainder )
Now from step 19, i.e.,, dividing 1 by 2, Step 2 to Step. 18 repeats thus giving
0
__________________ .
.
1 / 19 =
0.052631578947368421 or 0.052631578947368421
Note that we have completed the process of division only by using ‘2’. Nowhere the division by 19 occurs.
b) Multiplication Method: Value of 1 / 19
First we recognize the last digit of the denominator of the type 1 / a9. Here the last digit is 9.
For a fraction of the form in whose denominator 9 is the last digit, we take the case of 1 / 19 as follows:
For 1 / 19, 'previous' of 19 is 1. And one more than of it is 1 + 1 = 2.
Therefore 2 is the multiplier for the conversion. We write the last digit in the numerator as 1 and follow the steps leftwards.
Step. 1 :
1
Step. 2 : 21(multiply 1 by 2, put
to left)
Step. 3 : 421(multiply 2 by 2, put to left)
Step. 4 :
8421(multiply 4 by 2, put to left)
Step. 5 :
168421 (multiply 8 by 2 =16,
1
carried over, 6 put to left)
Step. 6
:
1368421 ( 6 X 2 =12,+1
[carry over]
= 13, 1
carried over, 3 put to left )
Step. 7 : 7368421 ( 3 X 2, = 6 +1 [Carryover]
= 7, put to left)
Step. 8 : 147368421 (as in the same
process)
Step. 9 : 947368421 ( Do – continue to step 18)
Step. 10 : 18947368421
Step. 11 : 178947368421
Step. 12 :
1578947368421
Step. 13 :
11578947368421
Step. 14 :
31578947368421
Step. 15 :
631578947368421
Step. 16 :
12631578947368421
Step. 17 : 52631578947368421
Step. 18 : 1052631578947368421
Now from step 18 onwards the
same numbers and order towards left continue.
Thus 1 / 19 =
0.052631578947368421
It is interesting to note that
we have
i) not at all
used division process
ii) instead
of dividing 1 by 19 continuously, just multiplied 1 by 2 and continued to multiply
the resultant successively by 2.
Observations :
a) For
any fraction of the form 1 / a9 i.e.,, in whose denominator 9 is the digit in the units place and a is the set of remaining digits, the value of the fraction is in
recurring decimal form and the repeating block’s right most digit is 1.
b) Whatever
may be a9, and the numerator, it is enough to follow the said process with (a+1)
either in division or in multiplication.
c) Starting from
right most digit and counting from the right, we see ( in the given example 1 /
19)
Sum of 1st digit + 10th digit = 1 + 8 = 9
Sum of 2nd
digit + 11th digit = 2 + 7 = 9
- - - - - - - - -- - - - - - - - - - - - - - - - - - -
Sum of 9th digit + 18th digit = 9+ 0 = 9
From the above observations, we conclude that if we find first 9 digits, further
digits can be derived as complements of 9.
i) Thus at the step 8 in division process we have 0.052631517 and next step. 9
gives 0.052631578
Now the complements of the numbers
0, 5, 2, 6, 3, 1, 5, 7, 8 from 9
9, 4, 7, 3, 6, 8, 4, 2, 1 follow the right order
i.e.,, 0.052631578947368421
Now
taking the multiplication process we have
Step. 8 : 147368421
Step. 9 : 947368421
Now the complements of 1, 2, 4, 8, 6,
3, 7, 4, 9 from 9
i.e.,, 8, 7, 5, 1, 3, 6, 2, 5, 0 precede in successive steps, giving the answer.
0.052631578947368421.
d) When we get (Denominator – Numerator) as the product in the multiplicative
process, half the work is done. We stop the multiplication there and
mechanically write the remaining half of the answer by merely taking down
complements from 9.
e) Either division or multiplication process of giving the answer can be put in
a single line form.
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