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

Thanks for the explanation. It cleared my doubt.

Why is 1 added to 15 in the last step?

I am not able to understand it. Why one is added at the last step?

Nice explanations thanks for the help.

Thank you.

We know that 1st bell will commence on 0 min. Then in 30 min, 15 other bells will be tolling at every 2 min. Of interval. Therefore if we add all of these. Answer will be 15 + 1=16.

I cannot understand why 1 is added in the last step?

Thanks @Balaraju Hari.

I got the easiest way to understand the solution that how the answer is 16.

Look at your clock it starts from 12:00 and ends at 12:00.
Now consider each hour of your clock as a minute that means 12 to 1=1 min and 1 to 2=2min. So for 2min it's 12 to 2 = 2min.

Now starting from 12:00 start counting for 2 minutes interval taking 12:00 as 1(times the ring bell together).

So, 12:00 - 1
12:00 to 2:00 - 2 (2nd time they rang together)
2:00 to 4:00 - 3
.
.
.
.
.
10:00 to 12:00 - 7 and now you have completed your 12 minutes out of 30 minutes.

Repeat the same process you will complete 24 minutes out of your 30 minutes and 13 times the bell rang together.

Now you are left with 6 minutes.
so 12:00 - 2:00 = 14 times.
2:00 - 4:00 = 15 times.
4:00 - 6:00 = 16 times.

Finally, you have completed your 30 minutes and the bell rang 16 times.

Hope now you people could understand how the answer is 16.

@All.

Here, we should count 0 but 0 is the 60th second of the previous minute if we count this 0 it would be 30 minutes 1 second.

So please give me the correct solution.

Can you please tell me how to calculate LCM? I am not understanding.