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. 17)
17.
What will be the least number which when doubled will be exactly divisible by 12, 18, 21 and 30 ?
196
630
1260
2520
Answer: Option
Explanation:

L.C.M. of 12, 18, 21 30 2 | 12 - 18 - 21 - 30

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= 2 x 3 x 2 x 3 x 7 x 5 = 1260. 3 | 6 - 9 - 21 - 15

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Required number = (1260 รท 2) | 2 - 3 - 7 - 5

= 630.
Discussion:
30 comments Page 2 of 3.

Appalaraju said:   10 years ago
Because it is already considered as it doubled in question only so please read questions and ask your doubts 630 is right answer.

Deepak said:   1 decade ago
1260/2 come ,because in Q it ask to find least no.(630) which when double to divisible by given no.(12,18,21,30)

Rajesh said:   9 years ago
The double of 1260 = 158760 is also divisible by 12, 18, 21, 30.

So, why can't option (c) 1260 be the answer?

Aadhithyaa said:   1 decade ago
They have told that the required number= (1260/2) = 630, where did that to which divides 1260 come from?

Saras said:   1 decade ago
why we are dividing by 2?? pl tel me and also tel me some easy tricks for h c m and l c m

Teja said:   10 years ago
Here, they have given number "which when doubled ", which mean 1260 /2 = 630.

Akshara said:   1 decade ago
Double in actual means x*x i.e x^2. The question is perceived as x*2.

Mobin said:   7 years ago
Can anyone say what is HCF of 12, 18, 21, 30?

Please explain it.

Aasritha said:   9 years ago
Thank you Parnassus for it. I didn't understand it first.

Vradhi said:   4 years ago
But 630 is not exactly divisible by 12 it's 52.5.
(12)


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