# L.C.M & H.C.F aptitude question and solution Tutorial-2

How important L.C.M and H.C F at competitive Arithmetics section? You know the importance of this math chapter very well. We are not talking on about that. Because we had given the core concept and formula of the number system in the L.C.M and H.C.F shortcut formula. Today, we are going to give you some important quantitative aptitudes to solve math problems. The previous tutorial was based on the number system and had given you the shortcuts formula and solution of some important aptitude which was prepared on the basis of numbers. Today, we are going to discuss some quantitative aptitudes which are based on the problem of our real-life. We have followed to prepare aptitude question which has already followed by the examiner in previous years question of SSC CHSL, CGL, PSC, I.B, Railway Recruitment exam, Banking exams and some others popular competitive examinations. So, let's look at the below few solved aptitude questions.

## Aptitude 1: Three bells ring at the interval of 20, 30 and 40 minutes respectively. If all bells were rung at 9 a.m, then when will ring all bells in next time?

Solution by math tricks: Here we have to find the L.C.M of 20, 30 and 40 minutes. Then the L.C.M value (minutes) convert into hours. Then we have to add that with 9 a.m. You can solve it easily without any copy pen. The L.C.M of 20, 30and 40 is 120. 120 minutes =2hours. So the next time all bells will ring at 9:00 a.m + 2hours=11:00 am.
Problem 2: