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Both a, b, and c are 3-digits integers, where a=b+c. Is the

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Manager
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Both a, b, and c are 3-digits integers, where a=b+c. Is the [#permalink]

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New post 27 Jun 2009, 22:30
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A
B
C
D
E

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. Both a, b, and c are 3-digits integers, where a=b+c. Is the hundreds' digit of number a equal to sum of that of b and c?
1). Tens' digit of a=tens' digit of b+tens' digit of c
2). Units' digit of a=units' digit of b + units' digit of c

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Re: DS digits [#permalink]

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New post 28 Jun 2009, 19:38
C.

Let the number be as follows
a = 100D + 10E + F
b = 100G + 10H + I
c = 100J + 10K + L

As per question
a = b + c
100D + 10E + F = (100G + 10H + I) + (100J + 10K + L)

stmt 1.
E = H + K
Not suff. as the sum of LHS and RHS can be influenced by G,J,I and L.

Stmt. 2
F = I + L
Not suff. due to same reason as for stm. 1.

Combine
100D + 10E + F = 100G + 100J + 10h + 10K + I + L
100D + 10E + F = 100G + 100J + 10(h+k) + F
100D + 10E + F = 100(g+j) + 10E + F
Lookign at the above eq.
100D = 100(G+J)
or d = G+J.
Hence suff.

Pls. tell the OA.
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Re: DS digits [#permalink]

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New post 29 Jun 2009, 12:45
vcbabu wrote:
. Both a, b, and c are 3-digits integers, where a=b+c. Is the hundreds' digit of number a equal to sum of that of b and c?
1). Tens' digit of a=tens' digit of b+tens' digit of c
2). Units' digit of a=units' digit of b + units' digit of c


This is basically a problem that asks us to determine whether there were any numbers carried over from the previous units in the addition process.

1 - Not enough. We know if the tens' digits do not add up to 10, then nothing will be carried over. We know the tens' digits of B & C do not add to 10, but we don't know whether anything carried over from the addition of the units' digits, which might in turn push the sum of the tens' digits over 10.
2 - Also not enough for the same reason above. We know the addition of the units' digits won't carry over to the tens, but we don't know anything about the tens' digits.

Combined: Enough, we know neither the units nor the tens will carry over additional numbers, so the sum of the hundreds' digits will not include anything carried over.
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Re: DS digits [#permalink]

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New post 29 Jun 2009, 13:05
I think ans is A

Statement 1 can only be true when there are no carry forwards from units to tens, and also from tens to hundreds. Though i have not checked out all the alternatives as it would take a lot of time, i personally feel sufficiently confident about this, and would rather have it answered wrong than waste time in attempting to check all alternatives.

If there are no carry forwards from tens to hundreds, the sum of hundreds digits of b and c will be equal to that of a.
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Re: DS digits [#permalink]

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New post 15 Jul 2009, 11:00
Quote:
1). Tens' digit of a=tens' digit of b+tens' digit of c


the only thing that I can conclude from this statement is , nothing got carried from units place...but I cant tell whether anything got carried over to the hundreds place..

281
+372
------
653 <-- here tens digit of the result is still equal to the tens digit of b and tens digit of c

one more case

231
+321
------
552 <-- here nothing is carried forward still the statement 1 holds good.

I would say the answer be E.
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Re: DS digits [#permalink]

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New post 15 Jul 2009, 13:58
skpMatcha wrote:
------
653 <-- here tens digit of the result is still equal to the tens digit of b and tens digit of c



tens digit is not equal to that of b+c

8+7 = 15 and not 5; and 15 is not one single digit. So no carry forward is ensured.
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Re: DS digits [#permalink]

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New post 16 Jul 2009, 07:51
Thanks for the explanation. Looks like these notions are unique to GMAT.

like rounding to nearest number cant be recursive and only the digit next to the rounding position is rounded && and the example as this thread..

:)
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Re: DS digits [#permalink]

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New post 16 Jul 2009, 08:41
vcbabu wrote:
. Both a, b, and c are 3-digits integers, where a=b+c. Is the hundreds' digit of number a equal to sum of that of b and c?
1). Tens' digit of a=tens' digit of b+tens' digit of c
2). Units' digit of a=units' digit of b + units' digit of c



I also think it should be A as there is no carry forward from the tens digit. Anyway whats the OA ?

Cheers
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Re: DS digits [#permalink]

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New post 17 Jul 2009, 06:41
Hi Guys, can someone explain why answer is "A"?
Thx in advance

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Re: DS digits   [#permalink] 17 Jul 2009, 06:41
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