Aptitude - Square Root and Cube Root - Discussion

Discussion Forum : Square Root and Cube Root - General Questions (Q.No. 3)

Square Root and Cube Root

The least perfect square, which is divisible by each of 21, 36 and 66 is:

213444

214344

214434

231444

Answer: Option

Explanation:

L.C.M. of 21, 36, 66 = 2772.

Now, 2772 = 2 x 2 x 3 x 3 x 7 x 11

To make it a perfect square, it must be multiplied by 7 x 11.

So, required number = 2² x 3² x 7² x 11² = 213444

Discussion:

80 comments Page 4 of 8.

Sams said: 1 decade ago

21, 36,66 which is divisible by 6
then we have to check hw many answer divisible by 6 and find the least one

Sandeep said: 1 decade ago

L.C.M: 21, 36, 66 then we have, 2*2*3*3*7*11.

Now square all these term.

Eg: 4*4*9*9*49*121 = 213444.

Nancy said: 1 decade ago

I totally cant understand the logic why we have to multiply 7 and 11. Can anyone explain this clearly?

Neelraj said: 9 years ago

It is multiplied by 7 so that we get 7^2 and 11 because we get 11^2. So perfect square is obtained.

Aandal Priyadarshini said: 1 decade ago

Shall we divide it by 2 and 3 either multiplying it by 7 and 11, explain this plz anybody.

Atul said: 1 decade ago

2/21,36,66

2/21.18,33

3/21,9,33

3/7,3,11

/7,1,11

So L.C.M : 2*2*3*3*7*11 = 2772.

Harish said: 9 years ago

Is there any other method to solve the question? If yes please tell me the trick.

Ravi said: 1 decade ago

Simply a no is divided by some other nos that nos factor must be divided that no.

Giftson David said: 1 decade ago

How did u get 7^2 and 11^2?
Should have calculated as 2^2 x 3^2 x 7 x 11 right..?

Sangeetha said: 1 decade ago

@Sneha

I didn't get last 2 steps in your solution, please can you help me.

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