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Digits

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beater GMAT Destroyer! Default Avatar
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Digits Post Mon Sep 29, 2008 6:43 am
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  • Lap #[LAPCOUNT] ([LAPTIME])
    If the units digit of the three-digit positive integer k is nonzero, what is the tens digit of k?
    (1) The tens digit of k + 9 is 3.
    (2) The tens digit of k + 4 is 2.

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    Morgoth GMAT Destroyer!
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    Post Mon Sep 29, 2008 8:00 am
    beater wrote:
    If the units digit of the three-digit positive integer k is nonzero, what is the tens digit of k?
    (1) The tens digit of k + 9 is 3.
    (2) The tens digit of k + 4 is 2.
    IMO A

    statement (1)

    let k = xyz [3 digit, unit digit non zero]

    x y z
    ++9
    ____
    x30

    minimum value of z can be 1 since it is non zero integer.
    1+9 = 10
    1 carry over to the tens y+1 = 3 , y =2

    maximum value of z can be 9
    9+9 = 18
    1 carry over to the tens y+1 = 3 , y =2
    Sufficient.

    Statement (2)

    x y z
    ++4
    ____
    x2(z+4)

    z=1, 1+4 = 5, y=2
    z=9, 9+4 = 13, 1 carry over, if y=1, tens digit will be 2. Insufficient.

    Thus, A.

    OA?

    beater GMAT Destroyer! Default Avatar
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    Post Mon Sep 29, 2008 5:23 pm
    OA - A

    Anyone with a different approach. Thanks!

    beater GMAT Destroyer! Default Avatar
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    Post Mon Sep 29, 2008 5:49 pm
    OA - A. Thanks!



    Last edited by beater on Tue Sep 30, 2008 4:56 am; edited 1 time in total

    Morgoth GMAT Destroyer!
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    Post Tue Sep 30, 2008 2:13 am
    What exactly is the OA, B or A?

    beater GMAT Destroyer! Default Avatar
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    Post Tue Sep 30, 2008 4:56 am
    Opps! Sorry for the mess. OA = A. Thanks!

    gmatguy16 Really wants to Beat The GMAT! Default Avatar
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    Post Tue Sep 30, 2008 6:15 pm
    can someone please explain how the oa is a,
    if number =122 ,then 122+9 =131,tens digit is 3
    if number =130, then 130+9=139 ,tens digit is 3 ,hence we have 2 different values of k ,2 and 3..did i mis u nderstood the question ?

    Morgoth GMAT Destroyer!
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    Post Wed Oct 01, 2008 4:16 am
    gmatguy16 wrote:
    can someone please explain how the oa is a,
    if number =122 ,then 122+9 =131,tens digit is 3
    if number =130, then 130+9=139 ,tens digit is 3 ,hence we have 2 different values of k ,2 and 3..did i mis u nderstood the question ?
    Units digit of the number cannot be 0. Therefore minimum value of the units digit can be 1 and maximum value can be 9. Try with these two values, yu should get the answer.

    gmattakers Just gettin' started! Default Avatar
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    Post Wed Oct 29, 2008 7:29 pm
    The answer in the OA is A

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    aj5105 GMAT Titan Default Avatar
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    Post Fri Jan 02, 2009 6:29 pm
    IMO A

    BTW neat expl !

    Morgoth wrote:
    beater wrote:
    If the units digit of the three-digit positive integer k is nonzero, what is the tens digit of k?
    (1) The tens digit of k + 9 is 3.
    (2) The tens digit of k + 4 is 2.
    IMO A

    statement (1)

    let k = xyz [3 digit, unit digit non zero]

    x y z
    ++9
    ____
    x30

    minimum value of z can be 1 since it is non zero integer.
    1+9 = 10
    1 carry over to the tens y+1 = 3 , y =2

    maximum value of z can be 9
    9+9 = 18
    1 carry over to the tens y+1 = 3 , y =2
    Sufficient.

    Statement (2)

    x y z
    ++4
    ____
    x2(z+4)

    z=1, 1+4 = 5, y=2
    z=9, 9+4 = 13, 1 carry over, if y=1, tens digit will be 2. Insufficient.

    Thus, A.

    OA?

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