# Thread: Number system problem (solving & explanations)

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## Number system problem (solving & explanations)

1.) What is the product of positive integer factor of 15?

A) 1 B)3 C)5 D)15 E)225

15 can only be factorised as 5 X 3 and they are not positive integers. Is the question correct? Ans given in the book:
SPOILER: 225

2) How many different factors are there for 242 excluding one and itself?

A)3 B)4 C)5 D)6 E)7

I am getting 2 ( 11 X 2 ) but the answer given is
SPOILER: B

3.) Two different numbers whgen divided by same divisor leave remainders 4 and 3 respectively and when their sum is divised by the same divisor, remainder is 1. What is the divisor?

A) 4 B)5 C)6 D)7 E)8

How to do this? Answer is:
SPOILER: C

4.) What is the least interger n such that 54/n^3 is positive.

A) -3 B)-1 C)1 D)2 E)3

I am getting D but the answer is
SPOILER: A

Any ideas?

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Originally Posted by riteshn
1.) What is the product of positive integer factor of 15?

A) 1 B)3 C)5 D)15 E)225

Factors of 15: 1, 3, 5 and 15. 1*3*5*15=225 ==>Answer E

2) How many different factors are there for 242 excluding one and itself?

A)3 B)4 C)5 D)6 E)7

Factors: -2, -11, 2 and 11 ===Answer B
I hope this help.

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1.) What is the product of positive integer factor of 15?
So by POSITIVE INTEGER they mean positive total or integers which are positive?

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1.) What is the product of positive integer factor of 15?
A) 1 B)3 C)5 D)15 E)225
Ans is E)225. the positive factors are 3, 5, 15 & their product is 225.

2) How many different factors are there for 242 excluding one and itself?
A)3 B)4 C)5 D)6 E)7
Ans. is B : 2, 11, 22, 121

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Originally Posted by riteshn
So by POSITIVE INTEGER they mean positive total or integers which are positive?
ritesh... positive integers mean integers that are positive... here for 15 the positive factors are 1, 3, 5, 15

and the negative factors if asked are -1, -3, -5, -15

6. Good post? |
Aaah....now I understood POSITIVE INTEGERS. Thanks. I misunderstood the FACTOR term too.

Any ideas on 3 & 4?

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Originally Posted by riteshn
4.) What is the least interger n such that 54/n^3 is positive.

A) -3 B)-1 C)1 D)2 E)3

?
is the Q (54/n)^3 or 54/n^3??

8. Good post? |
anyways...should'nt it be 1 since the smallest value of n is req.??

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(54)/n^3.

I think its a wrong one?

10. Good post? |
Originally Posted by riteshn
(54)/n^3.

I think its a wrong one?
Probably OA is wrong... ...

Q3. is driving me nuts!!