If N is a positive Integer, is the units digit of N equal to : GMAT Data Sufficiency (DS)
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If N is a positive Integer, is the units digit of N equal to

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If N is a positive Integer, is the units digit of N equal to [#permalink]

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If N is a positive Integer, is the units digit of N equal to zero?

(1) 14 and 35 are factors of N
(2) N = (2^5)(3^2)(5^7)(7^6)
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Re: DS Question [#permalink]

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New post 20 Mar 2010, 16:02
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meaglesp345 wrote:
If N is a positive Integer, is the units digit of N equal to zero?

1) 14 and 35 are factors of N
2) N = (2^5)(3^2)(5^7)(7^6)

I need help with an explanation on why # 2 is a sufficient answer.

Thanks for any help.


1) 14 = 2 * 7, 35 = 5 * 7

If a number has prime factors both 2 and 5, then it's divisible by 10 thus the unit digit equal to zero.

2) (2 * 5)^5 = 10,000

10,000 * 3^2 * 5^2 * 7^6

The unit digit has to be 0.

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Re: DS Question [#permalink]

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New post 24 Mar 2010, 09:20
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Im not sure that Statement 1 is sufficient on it's own. All we know from st1 is that N has prime factors of 2,5,7, and possibly others. From this, N could be 14, or 70 ...

But statement 2 is good because it tells you exactly the value of N. Keep in mind you dont have to figure it out, but you just have to know that if you had time, you could get a value for N and see what its units digit is.
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Re: DS Question [#permalink]

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New post 24 Mar 2010, 10:11
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I think it's D.

St. 1 : 14 = 2 * 7, 35 = 5 * 7, hence, 2,5,7 are factors of N.
If N=70, 35 * 2 or 14 * 5
If N=105, 35*3, 14 isn't a factor of 105.
If N = 140, 35 * 4, 14 * 10

Thus, when 14 and 35 are factors of N, the unit's digit is always 0 ! Hence, Sufficient.

St.2 : N=(2^5)(3^2)(5^7)(7^6)

As you have 2*5 here, the unit's digit will always be 0. Hence, Sufficient.
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Re: If N is a positive Integer, is the units digit of N equal to [#permalink]

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Re: If N is a positive Integer, is the units digit of N equal to [#permalink]

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New post 30 Jun 2014, 22:41
meaglesp345 wrote:
If N is a positive Integer, is the units digit of N equal to zero?

(1) 14 and 35 are factors of N
(2) N = (2^5)(3^2)(5^7)(7^6)


Bunnel: If you could throw some light particularly on statement (1), it would be great.

I am still not clear how even statement (2) ensures that unit digit will be zero.
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Re: If N is a positive Integer, is the units digit of N equal to [#permalink]

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patternpandora wrote:
meaglesp345 wrote:
If N is a positive Integer, is the units digit of N equal to zero?

(1) 14 and 35 are factors of N
(2) N = (2^5)(3^2)(5^7)(7^6)


Bunnel: If you could throw some light particularly on statement (1), it would be great.

I am still not clear how even statement (2) ensures that unit digit will be zero.


If N is a positive Integer, is the units digit of N equal to zero?

(1) 14 and 35 are factors of N --> N is divisible by 2 and 5, hence it's divisible by 10 --> the units digit must be 0. Sufficient.

(2) N = (2^5)(3^2)(5^7)(7^6). The same here 2 and 5 ensure that N is divisible by 10. Sufficient.

Answer: D.

Hope it's clear.
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Re: If N is a positive Integer, is the units digit of N equal to [#permalink]

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New post 29 Sep 2015, 21:13
Bunuel wrote:
patternpandora wrote:
meaglesp345 wrote:
If N is a positive Integer, is the units digit of N equal to zero?

(1) 14 and 35 are factors of N
(2) N = (2^5)(3^2)(5^7)(7^6)


Bunnel: If you could throw some light particularly on statement (1), it would be great.

I am still not clear how even statement (2) ensures that unit digit will be zero.


If N is a positive Integer, is the units digit of N equal to zero?

(1) 14 and 35 are factors of N --> N is divisible by 2 and 5, hence it's divisible by 10 --> the units digit must be 0. Sufficient.

(2) N = (2^5)(3^2)(5^7)(7^6). The same here 2 and 5 ensure that N is divisible by 10. Sufficient.

Answer: D.

Hope it's clear.


I opted B.

Bunnel..I am having doubts with statement 1. It just says 14 & 35 are factors of N, but it doesn't specify whether they are the only factors. If they aren't, then 1 isn't sufficient on its own. How can we infer that they are the only factors, when it's not clearly specified.
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Re: If N is a positive Integer, is the units digit of N equal to [#permalink]

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New post 29 Sep 2015, 21:40
Feluram wrote:
Bunuel wrote:
patternpandora wrote:
Bunnel: If you could throw some light particularly on statement (1), it would be great.

I am still not clear how even statement (2) ensures that unit digit will be zero.


If N is a positive Integer, is the units digit of N equal to zero?

(1) 14 and 35 are factors of N --> N is divisible by 2 and 5, hence it's divisible by 10 --> the units digit must be 0. Sufficient.

(2) N = (2^5)(3^2)(5^7)(7^6). The same here 2 and 5 ensure that N is divisible by 10. Sufficient.

Answer: D.

Hope it's clear.


I opted B.

Bunnel..I am having doubts with statement 1. It just says 14 & 35 are factors of N, but it doesn't specify whether they are the only factors. If they aren't, then 1 isn't sufficient on its own. How can we infer that they are the only factors, when it's not clearly specified.


The question asks whether the units digit of N equals to zero. From (1) N is divisible by 2 and 5, hence it's divisible by 10, which means that the units digit of N is 0. We don't care about other factors of N at all.
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Re: If N is a positive Integer, is the units digit of N equal to   [#permalink] 29 Sep 2015, 21:40
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