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 6 of 16.

Akshitha said:   7 years ago
Thnks @Sanchay.
(1)

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.

Princely said:   7 years ago
Can we try it in this way?

3+3+6+0= 12
2+2+4+0= 8,
5+6+0+0= 11,
12+8+11= 31,
3+1= 4.
(1)

Kashi said:   8 years ago
Thanks @Prakash.

Aman Srivastava said:   8 years ago
Thanks @Yogesh.

Gopika said:   8 years ago
@Saraswati.

I can't understand why you are multiplying 10?

Please explain it.

Samir Alvani said:   8 years ago
When you divide 1305, 4665 and 6905 by 1120 you will get the same remainder 185 so N is 1120 so the sum of the digits is 1+1+2+0=4.

Sibaram said:   8 years ago
What if the question is for finding smallest such number? Is it same like we have to find lcm of difference between numbers?

Guru prasad said:   8 years ago
Subtract the numbers such as,

4665-1305 = 3360 and 6905 - 4665 = 2240 then subtracting the obtained results.

3360-2240 = 1120. Therefore 1 + 1 + 2 + 0 = 4.

Meher priyanka said:   8 years ago
N(q2-q1)=(4665-1305)=3360
N(q3-q2)=(6905-4665)=2240
N(q3-q1)=(6905-1305)=5600

N(q1+q2+q3)=3360+2240+5600=11200

N(1+1+2+0+0)=4.


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