Aptitude - Problems on H.C.F and L.C.M - Discussion

Discussion Forum : Problems on H.C.F and L.C.M - General Questions (Q.No. 14)
14.
The least number which when divided by 5, 6 , 7 and 8 leaves a remainder 3, but when divided by 9 leaves no remainder, is:
1677
1683
2523
3363
Answer: Option
Explanation:

L.C.M. of 5, 6, 7, 8 = 840.

Required number is of the form 840k + 3

Least value of k for which (840k + 3) is divisible by 9 is k = 2.

Required number = (840 x 2 + 3) = 1683.

Discussion:
87 comments Page 8 of 9.

Rohit said:   10 years ago
Please help me how we get k=2?

Vinay said:   10 years ago
Yes if there was no option for how to find k. I can also go with @Mukul.

Truptti said:   10 years ago
How get 840?

Mukul said:   10 years ago
What if there was no option for and, then how to find k?

Itsnoble said:   10 years ago
@Suchita.

What if we have 111111111? Sum equal 9 but not divisible by 9.

An exception but nice work in this case.

Siva said:   10 years ago
Finding the answer with the choose options is the best method but finding the value of k has some formula. That is what should know.

Ritvik said:   1 decade ago
Best possible way to add the digits in the option and check divisibility with 9.

Sunita said:   9 years ago
If there is no option is given, and the question is asking sum of that no what will we do?

Ayush said:   1 decade ago
L.C.M. Of 5, 6, 7, 8 = 840.

Required number is of the form 840k + 3.

We know that it is divisible by 9.

So, 840k+3 = 9x. (x being the quotient).

Now, k is found by just putting values starting from 1, 2, 3.

If we get the lowest value which when used in k makes equation divisible by 9, it will surely be 2.

Hope it helped.

Mohit said:   1 decade ago
For those who giving method of dividing options by 9 and leaving 0 as remainder. During actual tests question makers just pull out trick like they give options which are leaving 0 remainder after dividing by 9 and also these options are satisfying other conditions.

So examples like this must be solve by given method of solving equation, this is the fastest and reliable method.


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