Aptitude - Numbers - Discussion
Discussion Forum : Numbers - General Questions (Q.No. 37)
37.
A 3-digit number 4a3 is added to another 3-digit number 984 to give a 4-digit number 13b7, which is divisible by 11. Then, (a + b) = ?
Answer: Option
Explanation:
4 a 3 | 9 8 4 } ==> a + 8 = b ==> b - a = 8 13 b 7 |
Also, 13 b7 is divisible by 11 
(7 + 3) - (b + 1) = (9 - b)
(9 - b) = 0
b = 9
(b = 9 and a = 1) (a + b) = 10.
Discussion:
35 comments Page 4 of 4.
Leoarul said:
1 decade ago
13b7 to know the divisibility of 11, we have to subtract sum of odd placed numbers with sum of even placed numbers.
in 13b7 odd places are 7and3
even places are b and 1.
now got it.
in 13b7 odd places are 7and3
even places are b and 1.
now got it.
Neelu said:
1 decade ago
I could not understand this problem.
i.e. How we got (7+3) - (b+1) from 13b7 ?
i.e. How we got (7+3) - (b+1) from 13b7 ?
Kiran said:
1 decade ago
Soma-->
the number is divisible by 11 if the difference between the sum of its digit at odd places and the sum of its digit at even places is either 0 or number divisible by 11.
4 a 3 | ==> here a can either be 0 or 1
9 8 4 }
13 b 7 |==> so b can be either 8 or 9
but (7+3) - (b+1) should be divisible by 11 or 0
so b can't be 8. so b is 9 and a is 1.
hence (a+b) is 10.
the number is divisible by 11 if the difference between the sum of its digit at odd places and the sum of its digit at even places is either 0 or number divisible by 11.
4 a 3 | ==> here a can either be 0 or 1
9 8 4 }
13 b 7 |==> so b can be either 8 or 9
but (7+3) - (b+1) should be divisible by 11 or 0
so b can't be 8. so b is 9 and a is 1.
hence (a+b) is 10.
Soma said:
1 decade ago
I could not get why 13b7 divisible 11 was represented as (7+3) - (b+1). ?
BhargaV said:
1 decade ago
-> (7 + 3) - (b + 1)
simplify this u got (9 - b)
simplify this u got (9 - b)
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