If n is a positive integer, what is the tens digit of n ?

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If n is a positive integer, what is the tens digit of n ? [#permalink]

25 Feb 2011, 05:12

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If n is a positive integer, what is the tens digit of n ?
(1) The hundreds digit of 10n is 6.
(2) The tens digit of n + 1 is 7.

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Re: og ds 167 [#permalink]

25 Feb 2011, 05:29

If n is a positive integer, what is the tens digit of n ?

(1) The hundreds digit of 10n is 6.
Multiplication by 10 will shift all digits one to the left. Ten's digit of n must be 6.

e.g.
n=4324324242468<- 6 in tens place
10n=43243242424680<-hundred's digit in 6 because 0 occupied the units place and rest all of digits moved 1 to the left.

n=69<-6 in tens place
10n=690<-6 in hundreds place

Sufficient.

(2) The tens digit of n + 1 is 7.
n=69
n+1=70<-tens digit of n+1 is 7 when tens place of n=6

n=73
n+1=74<-tens digit of n+1 is 7 when tens place of n=7

Not Sufficient.

Ans: "A"
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Re: og ds 167 [#permalink]

25 Feb 2011, 06:32

It is easy to see that the information provided is enough to solve the problem. I think the main trick is that some may think A is not enough. Dividing any 6xx number by 10 wil yield 6 as a tens digit, so this is sufficient to solve the question.

Re: og ds 167 [#permalink] 25 Feb 2011, 06:32

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If n is a positive integer, what is the tens digit of n ?

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If n is a positive integer, what is the tens digit of n ?

If n is a positive integer, what is the tens digit of n ?

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