Aptitude - Square Root and Cube Root - Discussion

| 21 36 66
2| 21 18 33
2| 21 9. 33
3| 7. 3. 11.

==> 2*2*3*3*7*11.
=> 4*9*77,
=> 36*77,
=> 2772.

To make perfect square means, Make all digits square.

Already we have a square for 2 and 3,
Remaining make square i.e., 7^2. 11^2,

So, Totally....2772*11*7=213444.

21 is having a factor as 7 and 3.
So check each option whether it is divisible by 7 or not.
So option a is only divisible by 7.

7and 11 multiply because according to question make perfect square 2 and 3 is left square but 7 and 11 not a perfect square so 7and 11 make a perfect square so multiply 7 and 11.

Hi, @Nick! this is the way to take out lcm.

Suppose the number is 27 now,
27will not go with 2 but with 3 so we'll divide it with 3 as follow.
3/27
3/9
3/3
=1
So lcm =3*3*3.

So, in nutshell, we have to take a least no divisible by the given no and then whatever the quotient comes write it in the next line and then again divide that no divisible by least no and then the process continues until you get 1 at last keep solving and in the end write all the multiples together.

How to find out LCM? Someone help me.

How to find out least perfect square?

Please anyone explain in simple way.

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

Why multiplied by 7x11?

Remember it's the least common factor we looking for 21, 36 and 66.

Find the Lcm = 3 * 2 * 7 * 6 * 11 = 3 * 2 * 7 * 3 * 2 * 11 = 2772 (the 3*2 after 7 is a perfect square to replace the 6 that's in the initial equation coz 3*2 is 6).

3 and 2 are the highest common factors while 7 and 11 are the least because they both appear once. So multiply the Lcm (2772) with 7 and 11 and you get your answer;
That is 2772 * 7 * 11 = 213444.

Hope this helped someone understand better.