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 2 of 12.

Divya said:   5 years ago
Why we are using lcm here instead of hcf?
(7)

Angelina said:   5 years ago
How did we get 9999? Explain it.
(4)

Subanshika said:   2 years ago
Thanks everyone for explaining the answer in detail.
(4)

Rahul said:   6 years ago
As question given greatest number then how we do LCM method ? Greatest number means HCF nah?
(3)

Mkp said:   7 years ago
Why we take LCM of these Numbers?

Why Not HCF? Can Anyone explain?
(2)

Prathyusha said:   6 years ago
How to identify whether the question given is based on LCM or HCF?
(2)

PRAKASG said:   9 years ago
Nice explanation.
(1)

Mahima said:   9 years ago
Find the greatest 3-digit number which is exactly divisible by 4,8 and 12?

Anyone solve this?
(1)

Tina said:   9 years ago
Please explain me if the 2 are already repeated in 25 then why you have taken for 3 times?
(1)

Subir shahu said:   6 years ago
Sure the greatest 4 digit no. is 9999.
Here we have to find the greatest 4 digit number divisible by 15,25,40 and 75( that is the number divisible by 600 as the LCM of 15,25,40 and 75 is 600).it means the greatest 4 digit number divisible by 600 is only the greatest number divisible by 15,25,40 and 75.

To find 4 digit greatest number here we must find the nearest 4 digit number less 9999 that is possible by dividing the 9999 by the LCM and subtracting LCM.

=> 9999÷600
=> 9999-(600*16)
=>9999-(9600)
=>399 is remainder.

We can calculate the required number by subtracting 399= 9999-399 or,
we can directly find the nearest number divisible by 600= 600*16=9600.
(1)


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