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. 4)
4.
Let N be the greatest number that will divide 1305, 4665 and 6905, leaving the same remainder in each case. Then sum of the digits in N is:
4
5
6
8
Answer: Option
Explanation:

N = H.C.F. of (4665 - 1305), (6905 - 4665) and (6905 - 1305)

  = H.C.F. of 3360, 2240 and 5600 = 1120.

Sum of digits in N = ( 1 + 1 + 2 + 0 ) = 4

Discussion:
158 comments Page 15 of 16.

Sanchay said:   7 years ago
We subtracted 1305 from 4665, 4665 from 6905 and 1305 from 6905 because we needed n as a common factor which can be obtained this way.

Let us consider 1305 as q1
4665 as q2
And 6905 as we
Then,

4665-1305 = N(q2 -q1).
6905-4665 = N(q3-q2 ).
6905-1305 = N(q3-q2 ).

Now we get here N as the factor of all 3 digits and we need to find the greatest factor so, take out the HCF of all three numbers i.e 1305, 4665, 6905 = 1120.

And this is your answer if your question asks no. Of digits in the number simply add the digits i.e 1+1+2+0=4.

Hope this helped.

Kotresh said:   7 years ago
Good explanation, Thanks @Yogesh.

Sachin said:   7 years ago
Thanks @Saraswati.

Harini said:   6 years ago
@Anchit.

We should subtract remainder. i.e 12-2=10.

GIRISH SINGH BISHT said:   6 years ago
Thanks for explaining @Priya.

K.manoj said:   6 years ago
Thanks @Saraswati.

Vishnu Sai said:   6 years ago
I have a question.

Can anyone please explain why they are taking the HCF of (4665-1305), (6905-4665) and (6905-1305) i.e. the HCF of 3360, 2240 and 5600.

Also in the question it states the remainder should be same, it does not state the remainder should only be zero.

So I wish some of the other clarifies my doubts.

Anom said:   6 years ago
Great explanation, Thanks @M. Harish.

Jaya said:   5 years ago
Thanks @Saraswati.

Prince Khan said:   5 years ago
Thanks for the answer @Saraswati.


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