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by CaptainHaddock » Mon Oct 31, 2011 10:25 am
P and N are natural numbers. If P^N has the same unit's digit as P, how many possibilities exist for the unit's digit of P?

(A) 1
(B) 2
(C) 3
(D) 4
(E) 5

Would like to know the methodology. OA is D
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by gmatblood » Mon Oct 31, 2011 10:32 am
CaptainHaddock wrote:P and N are natural numbers. If P^N has the same unit's digit as P, how many possibilities exist for the unit's digit of P?

(A) 1
(B) 2
(C) 3
(D) 4
(E) 5

Would like to know the methodology. OA is D
the digits are 0,1,5,6 = 4(d)
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by saketk » Thu Nov 03, 2011 11:17 am
CaptainHaddock wrote:P and N are natural numbers. If P^N has the same unit's digit as P, how many possibilities exist for the unit's digit of P?

(A) 1
(B) 2
(C) 3
(D) 4
(E) 5

Would like to know the methodology. OA is D
Well I have a concern here-

1) what is the source of this question?
2) I can give you many more examples in addition to 1,5,6, and 0.

For example if p =3 and N = 5 then 3^5 = 243. this also satisfies the given condition.

If p= 7 and N= 5 then 7^5 = 16807. this also satisfies the given condition.

NONE OF THE OPTIONS SATISFY THIS CONDITION

Again, what is the source of this question?

NONE OF THE OPTIONS SATISFY THIS CONDITION
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by sam2304 » Thu Nov 03, 2011 5:25 pm
D is right.

P can take any value and N can take any value

only numbers ending with 0, 1, 5, 6 raised to power of N will have same unit's digit as P
Getting defeated is just a temporary notion, giving it up is what makes it permanent.
https://gmatandbeyond.blogspot.in/
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