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There's are a few rules going around here, and we need to figure out what those are to accurately answer this question.

For starters, we have a < b < c, with a being greater than 10. I also see that we're looking at a remainder for a^c / b, and a, b, c are all consecutive integers.

That means, a^c will be monstrously large - so we need to figure out things more logically.

Still, to assume things, I'd go with a = 100, b = 101, and c = 102. That means, we're looking for the remainder of 100^102 / 101. Now, here, the 100, whatever it is raised by, will give us a number that's a few gazillion bazillion and whatnot... with multiple zeroes at the end.

But is there a pattern to the remainders? We know such patterns can help negate any complete math.

I know divided 100 by 101 won't help in anyway, so I'll go for 100^2 / 101; that's 10,000 / 101. A bit of manual long-division - 1,000 / 101 leaves a remainder 91; 910 / 101, leaves a remainder of 1.

But will this remainder of 1 stay even in subsequent powers of 100? We can take: 1,00,000 / 101. A bit of manual long-division - 1,000 / 101 leaves 91; then 910 / 101 leaves 1, to which if we add the remaining three zeroes, we'll again arrive at a remainder of 91. Oops, it isn't 1.

Should we see 100^4? That's 100,000,000. Now, here - and trust me, this is the last of the complex maths - you realize that for each 10,000, dividing by 101 will give a remainder of 1, so as long as we're dealing in powers of 10,000, we'll get a remainder of 1. 100,000,000 = 10,000*10,000; so a remainder of 1.

In other words, for each EVEN power of 100, we'll get the remainder as 1.

That'll hold true for 100^102.

But you must have noticed, that the rules change for every odd power.

So, what will happen if we, instead, need to look at an odd set of numbers?

For the this, and for the sake of simplicity, we can go down to the smallest numbers that are permissible - 11, 12, and 13, as a, b, and c.

Now, we need the value of 11^13 / 12. As we're looking at odd powers, we can attempt to find a pattern with, first, 11^1. This, when divided by 12, will simply give us 11 as a remainder.

But for 11^3, which is 1331, when we divide this by 12, we get a remainder of - well, what do you know, 11 (easy long-division proves that).

If we continue doing the same, the 11 remainder sticks.

So, for odd powers, clearly, the remainder is b - 1 (as b = 12 here). And for even powers, the remainder is, clearly, 1. The answer is D = I & II only.



Bunuel
If a, b, and c are consecutive integers, where 10 < a < b < c, which of the following could be the remainder when a^c is divided by b?

I. 1
II. b - 1
III. b

A. I only
B. II only
C. III only
D. I and II only
E. I and III only

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Bunuel
If a, b, and c are consecutive integers, where 10 < a < b < c, which of the following could be the remainder when a^c is divided by b?

I. 1
II. b - 1
III. b

A. I only
B. II only
C. III only
D. I and II only
E. I and III only

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Given that a,b,c are consecutive integers greater than 10.

Case 1:

a = 11, b =12 and c =13

Case 2:

a=12, b =13, and c =14

Remainder when a^c when divided by b = ?

Case 1:

(11)^13/12

When 11 is divided by 12 , we get a remainder 11 or -1.

(-1)^13 = -1 = 11 =a

a can be written as b-1 .

Case 2:

(12)^14/13

When 12 is divided by 13 , we get either 12 or -1.

(-1)^14 = 1

So, remainder 1 is possible.

Why can’t Remainder be b ?

Because, while dividing by b, if the remainder has been b, then it would be divided completely leaving remainder 0.

Option D
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Two cases:
a - even, b - odd, c - even
Example = 12, 13, 14
\(12^{14}\\
(13 - 1)^{14}\)
Remainder will be \((-1)^{14} = 1 \)
So I is possible.

a - odd, b - even, c - odd
Example = 11, 12, 13
\(11^{13}\\
(12 - 1)^{13}\)
Remainder wil be \((-1)^{13} = -1 = 11 \)
11 is nothing but b -1 (12 - 1), so II is possible.

III is never possible as the remainder should always be less than the divisor(b here).

Option D
Bunuel
If a, b, and c are consecutive integers, where 10 < a < b < c, which of the following could be the remainder when a^c is divided by b?

I. 1
II. b - 1
III. b

A. I only
B. II only
C. III only
D. I and II only
E. I and III only

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Lets make the numbers have a similar variable so we have a, a+1 and a+2
So the remainder when a^a+2/a+1
Since a= -1 (mod a+1) thus we have
a^a+2= (-1)^a+2 (mod a+1)
Meaning if a+2 is even (-1)^a+2= 1 so the remainder when divided by a+1 =1
However if a+2 is odd then (-1)^a+2= -1=a (mod a+1) .
Since a= b-1 and a<a+1 then remainder becomes b-1
Option three is not possible because a remainder has to be less than the divisor
Hence only I & II are possible
Ans D
Bunuel
If a, b, and c are consecutive integers, where 10 < a < b < c, which of the following could be the remainder when a^c is divided by b?

I. 1
II. b - 1
III. b

A. I only
B. II only
C. III only
D. I and II only
E. I and III only

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We are given c>b>a>10

Range of remainders when a^c/b is asked

Since remainder can never be equal to divisor, III is out.

If a=11 and b=12 and c=13, the remainder is b-1, or else if c=14, the remainder is 1.

Therefore, Option D imo
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a = b-1, c = b+1
a mod b = b-1 or -1
a^(b+1) mod b = (b-1)^(b+1) mod b = (-1)^(b+1)

If b+1 odd then remainder is -1 which means b-1, if b+1 even then remainder is 1

Answer: D


Bunuel
If a, b, and c are consecutive integers, where 10 < a < b < c, which of the following could be the remainder when a^c is divided by b?

I. 1
II. b - 1
III. b

A. I only
B. II only
C. III only
D. I and II only
E. I and III only

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Answer: D. I and II only

Why?

- 10<a<b<c -> meaning a,b,c = 1,2,3,..,9

III. b is Incorrect --> a^c /b -> anything divided by b, the remainder must not be b -> because a^c is divisible by b

II. b-1 is correct --> remainder can be any number under b

I. 1 is correct --> pick example 2^3 / 7 = 1 with remainder 1, so could be true




Bunuel
If a, b, and c are consecutive integers, where 10 < a < b < c, which of the following could be the remainder when a^c is divided by b?

I. 1
II. b - 1
III. b

A. I only
B. II only
C. III only
D. I and II only
E. I and III only

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a,b,c are consecutive integers so:
a=b-1, c=b+1
a^c=(b-1)^b+1
Work on b: (b-1)^b+1=( -1)^b+1
if b is even the b+1is odd and = -1=b-1
ib b is odd the b+1 is even ad = +1
so the remainder can be 1 or b-1
Final Answer:I & II only
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Note - could be and not must be.
acc to question: 10 < x < x +1 < x +2 -> x is an integer and remainder when (x^(x+2))/x+1 -> (-1)^x+2/x+1
putting value x = 11 -> (-1)^13/12 -> -1/12 => 11 which is b - 1
putting value x = 12 -> (-1)^14/13 -> 1/13 => 1 which is 1
further putting values yields same result hence only I and II.
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Since a, b and c are consecutive integers, b = a+1, c = a+2.
When dividing by b: a will give remainder −1.
Since a is just one less than b.

So, a^c =a^a+2 = (−1)^a+2 (mod b) when dividing b.

If a+2 is even, the remainder is 1.
If a+2 is odd, the remainder is −1, which is the same as b−1.
A remainder can never equal b.
So the possible remainders are 1 and b−1.

Answer IMO D: I and II only.
Bunuel
If a, b, and c are consecutive integers, where 10 < a < b < c, which of the following could be the remainder when a^c is divided by b?

I. 1
II. b - 1
III. b

A. I only
B. II only
C. III only
D. I and II only
E. I and III only

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If a, b, and c are consecutive integers, where 10 < a < b < c, which of the following could be the remainder when a^c is divided by b?

a,b,c are consecutive integers. Let, a=n, b=n+1, c=n+2 (n>10)

When a^c/b or we can write (n^(n+2))/(n+1)
We can also write n= (n+1)-1.
So, n ≡ -1 (mod n+1)
Hence we can write n^(n+2) = (-1)^(n+2) (mod n+1)
We need to check the power of (-1) whether it's odd or even

If n is even, then n+2 is also even.
(-1)^even = even
So the remainder is 1.

If n is odd, then n+2 is also odd.
(-1)^odd = odd
But the remainder can't be negative, so -1≡n (mod n+1)
Remainder here is n=b-1.

The remainders could be I.1 or II. b-1

I and II only
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let a, b & c is 11, 12, & 13 respectively 11^13/12 = (12-1)^13/12 would give last term -1 as power is odd so correct remainder would be -1 + 12 = b-1

Now let a, b & c is 12, 13 & 14 hence 12^14/13 = (13-1)^14/13 gives remainder 1 as power is even

so for all consecutive integers values of a, b & c remainder would be b-1 & 1 Ans - D
Bunuel
If a, b, and c are consecutive integers, where 10 < a < b < c, which of the following could be the remainder when a^c is divided by b?

I. 1
II. b - 1
III. b

A. I only
B. II only
C. III only
D. I and II only
E. I and III only

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All numbers are greater 10, hence the remainder can never be possible to b itseld when any number (a^c) is divided by b, since a is not zero or C is not infintely negative integer to make the resultant to be zero. 1 and b-1 are good possibilities. option D
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If a, b, and c are consecutive integers, where 10 < a < b < c, which of the following could be the remainder when a^c is divided by b?

I. 1
II. b - 1
III. b

A. I only
B. II only
C. III only
D. I and II only
E. I and III only

Let's do the trial and error method.

I. Let's consider a=11, b= 120, c =122

Remainder of (11^122)/120 or (121^61)/120 or 1^61/120 will be 1. Hence, 1 could be the remainder. but a, b, c are not consecutive numbers

a=11, b=12, c=13 ----> Remainder of 11^13/12 = 121^6/12 +11/12
Remainder of 1st part will be 1 but of second part will be 11...final remainder 11.

or (-1)^13/12 = 12-1 = 11 remainder.

a=12, b=13, c=14 ----> Remainder of 12^14/13 = (-1)^14/13 --Remainder will be 1...

II. Let's consider a=11, b=12, c= 13

Remainder of 11^13/12 which can be written as (-1)^13/12 will be 12-1= 11 = B-1


D is the answer, Since none of the option has all 3, we do not need to check further.
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assume 10,11,12,13 as the numbers where a is 11 and so on. Once u plugin these numbers, we can clearly see 12 can never be the remainder, because we are dividing these by 12. Also we can safely assume that 1 and 2 can be remainders.
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Since a b c are consecutive numbers greater than 10, we can write b and c as follows
b = a + 1
c = b + 1 = a + 2

To find the remainder when a^c is divided by b, we need to find the remainder when a is divided by b.
a ^ (a + 2) / (a + 1)

Since a = b - 1
((b - 1) ^ (a + 2)) / b
finding the remainder when (b - 1) is divided by b,
we get either 1 or b - 1 depending on the power (a + 2)

For example
let a = 11, b = 12, c = 13
then (11^13) / 12 gives remainder 11 which b - 1
Since a is odd, power is odd. So, (-1)^odd gives remainder -1. In these cases we get remainder as b - 1

let a = 12, b = 13, c = 14
then (12 ^ 14) /13 gives remainder 1
Since a is even, (-1)^even gives remainder as 1

So we can remainder 1 and b - 1.
Also, the divisor is b. So we cannot get remainder as b since remainder is always less than divisor.
Bunuel
If a, b, and c are consecutive integers, where 10 < a < b < c, which of the following could be the remainder when a^c is divided by b?

I. 1
II. b - 1
III. b

A. I only
B. II only
C. III only
D. I and II only
E. I and III only

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10<a<b<c
a=b-1
c=b+1

Let a=11, b=12, c=13

(a^c/b)R = [(b-1)^(b+1)/b]R = [11^13/12]R

[11/12]R = 11
[121/12]R = 1
[1331/12]R = 11....

Every odd power of 11 gives remainder as 11 and every even power of 11 will give remainder as 1.

So, [11^13]R = 11 = b-1

So, b-1 is a possibility

If a=12,b=13,c=14
[12^14/13]R

[12/13]R = 12
[144/13]R = 1

So for even power of 12, remainder will be 1.

Since a remainder is always less than the divisor, remainder can never be b

So, I and II are the only possible remainders

Option D.









Bunuel
If a, b, and c are consecutive integers, where 10 < a < b < c, which of the following could be the remainder when a^c is divided by b?

I. 1
II. b - 1
III. b

A. I only
B. II only
C. III only
D. I and II only
E. I and III only

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