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:
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 5 of 12.
Arunav said:
1 decade ago
There can be another approach. Just find the L.C.M. of the nos. The L.C.M. comes to be 600. Now check which is the greatest no. which is getting divided by 600.
Numbers of option B and option D are not getting divided by 600 and between option B and C (which are getting divided by 600) the number of option C is the greatest no. divisible by 600
In this way I guess it would be quicker than dividing 9999 and then subtracting the remainder.
Numbers of option B and option D are not getting divided by 600 and between option B and C (which are getting divided by 600) the number of option C is the greatest no. divisible by 600
In this way I guess it would be quicker than dividing 9999 and then subtracting the remainder.
Lakhan said:
1 decade ago
@Rahul
How can you ignore 75= 15 x 5 = 5 x 5 x 3 while calculating LCM ?
How can you ignore 75= 15 x 5 = 5 x 5 x 3 while calculating LCM ?
Lakhan said:
1 decade ago
Friends will you please explain how the LCM came 600 in detail ?
Sam said:
1 decade ago
Great explanation Debashree.
PK rojer said:
1 decade ago
Instead of calculating LCM Why we don't go for calculating HCF.
Dr.Deepshikha Saini said:
1 decade ago
Debashree you are superb. Thanks for such a wonderful explanation.
Akshata said:
1 decade ago
@Arunav.
Your explanation seems to be quick and fast. Can you elaborate and let me know who will it work.
My funds of finding LCM in this case 600 is clear.
But when you are writing "Numbers of option B and option D are not getting divided by 600 and between option B and C (which are getting divided by 600) the number of option C is the greatest no. Divisible by 600" is not clear. Just let me know the explanation.
In this way I guess it would be quicker than dividing 9999 and then subtracting the remainder.
Your explanation seems to be quick and fast. Can you elaborate and let me know who will it work.
My funds of finding LCM in this case 600 is clear.
But when you are writing "Numbers of option B and option D are not getting divided by 600 and between option B and C (which are getting divided by 600) the number of option C is the greatest no. Divisible by 600" is not clear. Just let me know the explanation.
In this way I guess it would be quicker than dividing 9999 and then subtracting the remainder.
Aslam said:
1 decade ago
Please calculate the remainder.
Alwin said:
1 decade ago
To find LCM
15=3*5
25=5*5
40=2*2*2*5
75=3*5*5
Every number written in the form of multiples of prime number
Now we will write as
15=> 3 5
25=> - 5 5
40=> - 5 - 2 2 2
75=> 3 5 5 - - -
___________________
3 5 5 2 2 2
Then
3*5*5*2*2*2=600
Hence the result
15=3*5
25=5*5
40=2*2*2*5
75=3*5*5
Every number written in the form of multiples of prime number
Now we will write as
15=> 3 5
25=> - 5 5
40=> - 5 - 2 2 2
75=> 3 5 5 - - -
___________________
3 5 5 2 2 2
Then
3*5*5*2*2*2=600
Hence the result
Dileep Kumar M B said:
1 decade ago
How a person could know whether to take LCM or HCF? can anybody explain me when should we use these LCM and HCF ?
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