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. 5)
5.
The greatest number of four digits which is divisible by 15, 25, 40 and 75 is:
9000
9400
9600
9800
Answer: Option
Explanation:

Greatest number of 4-digits is 9999.

L.C.M. of 15, 25, 40 and 75 is 600.

On dividing 9999 by 600, the remainder is 399.

Required number (9999 - 399) = 9600.

Discussion:
120 comments Page 9 of 12.

Nandha said:   1 decade ago
Why we have to subtract (9999-399)?

Gayathri Ganesan said:   1 decade ago
Magesh, I'm also getting confusion with that type of doing lcm brings 3000. Then how they put 600? Is anyone cleared this doubt?

David said:   1 decade ago
Because greatest no. of four digit is only 9999.

So we divide 9999 by 600. So please use your common sense.

V!cky said:   10 years ago
9800-9000 = 800.

9600-9400 = 200.

800-200 = 600.

Solved further get 399.

Prajnya.samantaray said:   10 years ago
Can any one please explain in which case I have to take the L.C.M and where H.C.F? I am really confused.

Amala said:   10 years ago
Any body please tell me how we get 399 remainder?

Gayathri said:   10 years ago
Is anybody got idea about different lcm value by two methods?

Darshan said:   10 years ago
Concept is simple.

The greatest 4 digit no in numbers is 9999.

Then find the LCM of 15, 25, 40, 75 = that is 600.

So if 9999 is divisible by 600 then it is the greatest 4 digit no.

If we divide 9999 by 600 it will leave a remainder 399.

600) 9999 (16
9600
--------
0399 --< this is remainder.

If we subtract it with dividend :: (9999-399) = 9600.

So the 9600 is divisible by 600 without leaving a remainder hence it is divisible by all given nos.

Kinjal said:   10 years ago
9999 is divided by 600.

Quotient: 16.

Remainder: 399.

Vivek Balodi said:   9 years ago
Why we take LCM of these Numbers ? Why Not HCF? Can Anyone explain ? When we have to take LCM and when HCF?


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