Aptitude - Numbers - Discussion

Discussion Forum : Numbers - General Questions (Q.No. 21)
21.
Which of the following number is divisible by 24 ?
35718
63810
537804
3125736
Answer: Option
Explanation:

24 = 3 x8, where 3 and 8 co-prime.

Clearly, 35718 is not divisible by 8, as 718 is not divisible by 8.

Similarly, 63810 is not divisible by 8 and 537804 is not divisible by 8.

Consider option (D),

Sum of digits = (3 + 1 + 2 + 5 + 7 + 3 + 6) = 27, which is divisible by 3.

Also, 736 is divisible by 8.

3125736 is divisible by (3 x 8), i.e., 24.

Discussion:
56 comments Page 2 of 6.

Raj said:   7 years ago
Why are we taking 3 and 8 only and not 4, 6 or 12, 2?
(1)

Shubham said:   8 years ago
@Rohit.

May be we need to consider only co-prime numbers to solve the question and we have already tricks to check if the number is divisible by 3 or 8.

Thiru said:   8 years ago
What is co-Prime?

Ronit said:   8 years ago
Why we take only 8*3=24? why not other?

Keerthi said:   8 years ago
35718 can be divisible by 3 and 8 then why can't we divide with 24?

Prakarsh said:   8 years ago
We can not take 2*3*4 because 2&4 are not co primes, hence for 24 only possible co-primes are 8*3.

CO-PRIME: Those prime numbers which have only '1' as a common factor.

THANK YOU

Amit Thakuri said:   8 years ago
@Somgopal.

Will you make me understand how did we got 736 and from where?

Neha said:   8 years ago
@Thiru.

A set of numbers which do not have any other common factor other than 1 are called co-prime.

Neha said:   8 years ago
Thanks @Naresh.

Yogi said:   8 years ago
I don't understand the methods. Please anyone tell me the shortcut method for solving this.


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