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. 10)
10.
The least multiple of 7, which leaves a remainder of 4, when divided by 6, 9, 15 and 18 is:
74
94
184
364
Answer: Option
Explanation:

L.C.M. of 6, 9, 15 and 18 is 90.

Let required number be 90k + 4, which is multiple of 7.

Least value of k for which (90k + 4) is divisible by 7 is k = 4.

Required number = (90 x 4) + 4   = 364.

Discussion:
88 comments Page 3 of 9.

Sai kowsalya.D said:   7 years ago
K=4 because 4 is d Perfect no that suits to d equation i.e (90k+4).

If we substitute k=4 then it becomes 364 hence 364 is divisible by 7 i.e 52 hence k=4.

Snehesh said:   9 years ago
In the equation,

AX + B,

-> A is the LCM of all the given values.
-> B is the remainder.
-> The first number of the form: 90A+4 is 364. Hence, the ans.

Anukriti said:   10 years ago
Is it for all cases we put the value of remainder in k; e.g if 7 is remainder then we should keep the value of k = 7? Is it general or anything else?

Srihari said:   1 decade ago
It can not be 1, 2, 3 because if we substitute these numbers the result which is not divisible by 7. Let's check out. The only least number is 4.

MMTbelieve youtube said:   2 years ago
We got till lcm 90 ,
Then N=90k+4 should be divisible by 4 then we will get n.
So, put k=1,2,3,4 on 4 the ans 364 is divisible by 7.
So N = 364.
(13)

Prince said:   8 years ago
@Priya it is so easy.

6 = 2 * 3
9 = 3 * 3
15 = 3 * 5
18 = 2 * 3 * 3.

Take one number from common multiple and multiply rest digits.
2*3*3*5.

Srishti said:   1 decade ago
Here is a simple logic.
First find the LCM of the no.s which comes 90.
Now find the no. among the options greater than 90 and divisible by 7.

Sagar Khare said:   4 years ago
@ALL.

Guys here you use divisibility rules.

We have to find 7 multiple so apply the simple divisibility rule of 7 on all the answers.
(23)

Shruti said:   8 years ago
You don't need to take anything on right-hand side. Just see whether the values of k when multiplied and added are a multiple of 7.

Sravanthi said:   1 decade ago
It is given in the question that it should be least multiple of 7 which leaves remainder 4. So why don't it be 94. Please clarify.


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