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. 11)
11.
Find the lowest common multiple of 24, 36 and 40.
Answer: Option
Explanation:
2 | 24 - 36 - 40
--------------------
2 | 12 - 18 - 20
--------------------
2 | 6 - 9 - 10
-------------------
3 | 3 - 9 - 5
-------------------
| 1 - 3 - 5
L.C.M. = 2 x 2 x 2 x 3 x 3 x 5 = 360.
Discussion:
21 comments Page 2 of 3.
Nikhil said:
10 years ago
24 = 2*2*2*3.
36 = 2*2*3*3.
40 = 2*2*2*5.
For 24 = 2*3*4. We can not take 4 because 4 is not prime no.
Same applies for 40 = 2x4x5. 4 is not prime so don't take it use 40 = 2x2x2x5.
36 = 2*2*3*3.
40 = 2*2*2*5.
For 24 = 2*3*4. We can not take 4 because 4 is not prime no.
Same applies for 40 = 2x4x5. 4 is not prime so don't take it use 40 = 2x2x2x5.
Sudheer said:
10 years ago
@Keerthi @Girika.
The LCM of 24, 36, 40 is 360 only, not 720. Once check it.
The LCM of 24, 36, 40 is 360 only, not 720. Once check it.
Mahesh said:
1 decade ago
If we do the LCM process with 6, 4, 2 as divisors we are getting the LCM as 720 and with the numbers 2, 2, 3, 2 as divisors we are getting 360 as LCM.
Why that difference is occurring and which one we should consider as LCM?
Why that difference is occurring and which one we should consider as LCM?
Sakshi said:
1 decade ago
We generally break the numbers into prime numbers.
So if 24 = 2*12 = 2*(3*4) = 2*3*2*2 = 2^3*3.
Follow this for the other numbers too. This is the shortcut and safest method.
So if 24 = 2*12 = 2*(3*4) = 2*3*2*2 = 2^3*3.
Follow this for the other numbers too. This is the shortcut and safest method.
Janu said:
1 decade ago
Is there any shortcut method for 3 digits number.
Jeevan said:
1 decade ago
24=2*2*2*3 ///24=2*3*4 not possible **use small numbers **.
36=2*2*3*3.
40=2*2*2*5.
Now take common from combination of 3 numbers i.e 2,2.
Now take common from combination of 2 numbers i.e 2,3.
Now use numbers which do not have pair i.e 3,5.
Now multiply 2*2*2*3*3*5=360.
Ans is 360.
36=2*2*3*3.
40=2*2*2*5.
Now take common from combination of 3 numbers i.e 2,2.
Now take common from combination of 2 numbers i.e 2,3.
Now use numbers which do not have pair i.e 3,5.
Now multiply 2*2*2*3*3*5=360.
Ans is 360.
Keerthi said:
1 decade ago
LCM is 720 How do you get 360?
Mahesh said:
1 decade ago
4|24 36 40
3|6 9 10
2|2 3 10
3|1 3 5
5|1 1 5
|1 1 1
4*3*2*3*5 = 360.
3|6 9 10
2|2 3 10
3|1 3 5
5|1 1 5
|1 1 1
4*3*2*3*5 = 360.
(1)
Girika said:
1 decade ago
This is wrong. LCM of 24, 36, 40 is 720.
Raviteja said:
1 decade ago
24=2*2*2*3=(2^3 * 3^1).
36=2*2*2*3*3=(2^3 * 3^2).
40=2*2*2*3*5=(2^3 * 3^1 * 5^1).
For L.C.M take largest power primes
L.C.M=2^3 * 3^2 * 5^1=2*2*2*3*3*5=360.
36=2*2*2*3*3=(2^3 * 3^2).
40=2*2*2*3*5=(2^3 * 3^1 * 5^1).
For L.C.M take largest power primes
L.C.M=2^3 * 3^2 * 5^1=2*2*2*3*3*5=360.
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