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Unit digit

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Unit digit

by gmat740 » Tue Jul 21, 2009 5:06 pm
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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Source: — Data Sufficiency |
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by shibal » Tue Jul 21, 2009 5:09 pm
IMO A

since they are non-zero digits, if we add 9 to 1 or another number, we will have 10,11,12 and so on... thus the tens digit in this case is 2.
stmt 2 doesn't really help, cuz it could be 39+2=41 or 41+2=43.. insuff
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by shargaur » Tue Aug 04, 2009 8:24 pm
Hi Shibal,

You misread Statement 2

(2) The tens digit of k + 4 is 2.

ie K(xyz) + 4=x'y'2

this is possible only when ones is 8. so if ones is 8..then to make y'=3 y must be 2..so its sufficient.
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by cubicle_bound_misfit » Tue Aug 04, 2009 9:35 pm
No stmt 2 is not

let the number be


XYZ where Z !=0

for Z+4 if Z<=5 Y remains as it is i.e Y could be 2 as given
+
if Z>5 tens digit Y becomes Y+1 i.e Y could be 1.
Hence Insufficient.

HTH
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