Aptitude - Numbers - Discussion

Discussion Forum : Numbers - General Questions (Q.No. 6)
6.
How many of the following numbers are divisible by 132 ?
264, 396, 462, 792, 968, 2178, 5184, 6336
4
5
6
7
Answer: Option
Explanation:

132 = 4 x 3 x 11

So, if the number divisible by all the three number 4, 3 and 11, then the number is divisible by 132 also.

264 11,3,4 (/)

396 11,3,4 (/)

462 11,3 (X)

792 11,3,4 (/)

968 11,4 (X)

2178 11,3 (X)

5184 3,4 (X)

6336 11,3,4 (/)

Therefore the following numbers are divisible by 132 : 264, 396, 792 and 6336.

Required number of number = 4.

Discussion:
61 comments Page 2 of 7.

Rushikesh said:   7 years ago
What is the divisibility property of 11?

Please, anyone, explain.

Lalitha said:   7 years ago
@All.

Here, We can take 6, but again 6 having the factors of 2*3.
(5)

Supraja said:   7 years ago
Please explain the answer shortly.
(1)

Merlin said:   7 years ago
What does it mean the required number of number is 4?
(1)

Nishant said:   8 years ago
462 is also divisible by 11 and gives 42 so why we won't take it?

It's answer should be 5.
(2)

Reshma said:   8 years ago
Can you give divisibility rule of more numbers?

Sushmitha said:   8 years ago
Dividing each of the numbers with 132 directly is a lengthy and difficult process. So we take coprime factors, i.e 4, 3, and 11
(That's nothing but 132 is the multiplication of 11*3*4 , so the no's which are divisible by these 3 are also divisible by 132)
Divisibility rule for 11 : Difference between sum of digits at odd places and sum of digits at even places is either 0 or a number that is divisible by 11.
Divisibility rule for 3 : sum of digits is divisible by 3.
Divisibility rule for 4 : last 2 digits is divisible by 4.
---------------------------------------------------------------------------------
Round 1 : Just by seeing we can clearly tell that 264, 396, 462,792, 6336 are divisible by 11.
Round 2 : Now we have to check if above 5 numbers are also divisible by 3 and 4.
But 462 is not divisible by 4, because the last 2 digits ie 62 is not divisible by 4. Rest 4 of these numbers above are divisible by both 3 and 4.

So, the final answer is 4.
(1)

Shiv said:   9 years ago
I don't understand why only we take 4, 3 and 11.

How I would be wrong if I take 2*11*3?
(3)

Adil said:   9 years ago
This is the wrong answer. In this logic, 462 can also divide by 4, 3, 11.

Anvesha said:   9 years ago
@Koala,

I guess you missed out on the fact that we in here are talking about co-primes while 4 and 2 don't happen to be co-prime factors. 88 = 8 * 11.

And 9988 is not divisible by 8.


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