If n is a positive integer, what`s the tens digit of n? 1)

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If n is a positive integer, what`s the tens digit of n? 1) [#permalink]

12 Mar 2011, 12:16

If n is a positive integer, what`s 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: tens digit [#permalink]

12 Mar 2011, 12:29

Madelaine88 wrote:

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

1) 10n will just add a 0 to the units place and shift every digit by 1 to the left; that's all.

If Hundred's place of 10n = 6; Ten's place of n must be 6
Sufficient.

2)
If n=69; n+1=70;
If n=73; n+1=74;

So; ten's place of n+1 is 7 for both the values discussed above.

Thus; ten's place of n may be 6 or 7.
Not sufficient.

Ans: "A"
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Re: tens digit [#permalink]

12 Mar 2011, 15:33

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

(1)10n that means n is multiplied by 10 and result is like 1670 (n=167). To become hundred digit 6 for 10n the tens digit must be 6. Suf.
(2) the tens here could be 6 could be 7 (69+1=70 or 72+1=73)
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Re: tens digit [#permalink]

12 Mar 2011, 18:31

Answer is A.

1. Is sufficient

10n - when n is multiplied by 10 - n's unit digit would become 10n's ten's digit
n's ten's digit would become 10n's hundred's digit

so n's ten's digit can be found from 10n's hundred's digit.

2. if there was a carry over in n +1 addition , then n's ten's digit would be 6
if there was no carry over in n+1 addition , then n's ten's digit would be 7
Not sufficient.

Re: tens digit [#permalink] 12 Mar 2011, 18:31

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If n is a positive integer, what`s the tens digit of n? 1)

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If n is a positive integer, what`s the tens digit of n? 1)

If n is a positive integer, what`s the tens digit of n? 1)

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