Aptitude - Problems on H.C.F and L.C.M - Discussion

Use divisibility rule and elimination:

As it is even, eliminate- option C.

Then we can observe two options have (3x3) ie 9. Check divisibility of 252 which is (2+5+2=9 )Hence divisible by 9 so eliminate option B.

As we see the option A has (2x2 ie 4) check divisibility of 4 (52/4=13).
Hence Option A is correct.

Check is it divisible by smaller prime number then bigger.

2|252
2|126
3|63
3|21
7|7
|1

Nice explanation, Thanks @Manish.

For bigger values do like this.

2 x 2 x 3 x 3 x 7.

1. Multiply first two digits : 2 x 2 = 4.

2. Then multiply answer with the 3rd digit: 4 x 3 = 12.

3. Then just multiply the Unit digit (last digit) with next digit : 2 x 3=6.

4. Then repeat 3rd step : 6 x 7 = 42.

5. Now, the last digit of the answer is "2" match it with the Unit digit of given number in question which is also "2".

Do it for all options, it will be easy after practice some questions.

How to find the solution for big values? Is there any shortcut method.

In this case we multiply small numbers 1st and then bigger one ones digit 2 that is your answer.

If we will get a bigger value then how can we find the answer.