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Data Sufficiency - Find value of B [#permalink]
 08 Nov 2009, 08:09
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If A, B and C are digits such that AB is not equal to 0, what is the value of B.
1. AB
+BA
AAC
2. A = 1.
I am confused with the answer explanation provided to me. need explanation.
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Re: Data Sufficiency - Find value of B [#permalink]
08 Nov 2009, 08:48
answer A
Statement 1:
AB + BA = AAC
10A + B + 10B + A = 100A + 10A + C
11A + 11B = 110A + C
11B -C = 99A
B = 9
C = 0
A = 1
19 + 91 = 110
B cannot equal 10 because the question assumes they are single digits
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Re: Data Sufficiency - Find value of B [#permalink]
08 Nov 2009, 09:07
kalpeshchopada7 wrote: If A, B and C are digits such that AB is not equal to 0, what is the value of B.
1. AB
+BA
AAC
2. A = 1.
I am confused with the answer explanation provided to me. need explanation. You can also go about it like following: AB BA --- AAC Left most A has to be 1 as it is carried over from previous addition (max possibility 9+9=18). So we can write: 1B B1 ---- 11C Now second row B has to be 9 to be able to carry over 1. So this changes to: 19 91 ---- 110 <-C calculated to be 0.
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Re: Data Sufficiency - Find value of B [#permalink]
08 Nov 2009, 09:20
Ok, i got my mistake. I was considering equation given in statement 1 to be the stem  The answer should be A only 
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Re: Data Sufficiency - Find value of B [#permalink]
09 Nov 2009, 23:48
smtripathi wrote: add the numbers:
10A+B
10B+A
------
10(A+B)+(A+B)
or, 11(A+B)
here , 11(A+B) signifies AAC that means AA means 11 and C means A+B
hence quick answer for A = 1.
For C, substitute the answers and you will see, C=0, since B=9 (B can't be zero) thankx .. this is cleaner way to do this kind of problems.
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Re: Data Sufficiency - Find value of B [#permalink]
10 Nov 2009, 01:28
smtripathi wrote: 10A+B
10B+A
------
10(A+B)+(A+B)
or, 11(A+B)
here , 11(A+B) signifies AAC that means AA means 11 and C means A+B
hence quick answer for A = 1.
For C, substitute the answers and you will see, C=0, since B=9 (B can't be zero) Thanks buddy... I was searching for some generic rule like this. thanks
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Re: Data Sufficiency - Find value of B [#permalink]
11 Nov 2009, 22:02
kalpeshchopada7 wrote: If A, B and C are digits such that AB is not equal to 0, what is the value of B.
1. AB
+BA
AAC
2. A = 1.
I am confused with the answer explanation provided to me. need explanation. I used this approach: Using 1---A,B#0 since A+B gives a different digit. Also, since AB+BA is giving a 3 digit #, When we add units place (B+A) we need to carry forward 1. When we add the ten's digit , we have A+B+1 giving the unit's place "A". This is only possible if B=9  So statement 1 is sufficient.
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Re: Data Sufficiency - Find value of B [#permalink]
12 Nov 2009, 09:28
Here is how I solved the problem:
From Statement 1:
I started by seeing what the problem would look like if we assumed A = 0
1B
+B1
11C
Possible!
Then seeing what it would look like if we assumed A = 2
2B
+B2
22C
Impossible! There is no way we can add two two digit numbers if and get over 200! So we know that A cannot be greater than 1.
From
1B
+B1
11C
It is easy to see that B must be a high number like 8 or 9 to hold true:
19
+91
110
SUFFICIENT!
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Re: Data Sufficiency - Find value of B
[#permalink]
12 Nov 2009, 09:28
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