Aptitude - Numbers - Discussion

@Sunny

462 is not divisible by 4.

The logic is some what like this...If a number is divisible by p and q then its also divisible by p*q(product of two nos),to the condition that p and q are co-primes..extending the rule to one more level..!!

But it is lengthy process. Divisible each number by all these three elements. Is there any shortcut to solve such type of questions ?

Hi,
its very easy to find whether a given no.is divisible by 3,4,11..
if sum of digits in the gn no. is divisible by 3..then the gn no.s divisible by 3.
if the last 2 digits('1's &'10' )is divisible by 4..then the whole no. is divisible by 4..
likewise,if sum of no.s in oddposition - sum of no.s in even position=0 then..the gn no is divisible by 11..
so..it is easy way to find the answer..
it s enough to know the simple rules of dividing process.

We take 4 instead of 2*2. Because all the numbers which are divisible by 4 also divisible by 2. And take the multiplication of same numbers.

I DIN'T understand the logic, Could u please explain it ?

Looking at the series we can conclude it is series

132 --
264 (132+ 132)
396 (264+132)
462 (396+132 = 528)not equal
792 (660+132)
968( 792+132= 924) not equal
therefore 924+132 = 1056
1056+1056 = 2112
2178 (1056 + 1056 = 2112) not equal
5184 (2112 +2112 + 1056= 5280) not equal
6336 (6204+132 = 6336) equal

Thank you senthi. I agree with your answer.

Hey guys.

First we take coprime factors, that's why we take 4,3,and 11 and not 2.

coprime nos are those no whose HCF is 1.

Hope now it is clear.;)

264, 396, 462, 792, 968, 2178, 5184, 6336
264, 396 and 792 are 2, 3, 6 multiples of 132 : leave them
7 multiple of 132 = 924 Hence omit 968
Similarly omit 462

2178 is not divisible by 4 ( last 2 digits)
5184 fails 11 divisibility test ((5+8=13); (1+4=5); 13-5 =8 is not a 11 multiple
6336 passes 3, 4, 11 divisibility tests
264, 396, 798 pass by observation divisibility by 132
6336 by detailed 3,4,11 divisibility pass

For 6336 alternate method is 50 times 132 is 6600
6600 -6336 = 264 - a multiple of 132: hence it passes.

Look. 4=2*2. If it is already can divide by 4, then what is the need to check it with again 2 because as we know If a number "A" is divisible by all factors of another number say "B", then "A" is divisible by "B".