Thanks Bobby. Some of the problems are classics indeed, but it is good to have all nice puzzles gathered in one place.
I think that the two paradigms are complementary: mathematics, brainteasers and puzzles are an essential ingredient in the thought honing process of a human being. They teach us how to structure our thought and construct scenarios from simple incremental steps. This is why, when lifting these "brain weights" the aim is to lift the weights(thinking) and not know how much the weight weighs(know the solution). However, when encountering problems in real life, the aim is to get things done. If the problem has been solved before, do not think much about it and be philosophical, just find your way through. When encountering a new problem which hasn't been solved before, this is where ingenuity and creativity kicks in and this is where your maths education pays off.

my 2 cents,
Bilal

WoOoOoW
tHaNk YoU So MuCh

are there the solutions ?

@Fermat'S: Anytime :-D. As explained in the home section, no solutions are provided. If you give enough thoughts to a puzzle and feel you are stuck, I am happy to give a hint or check your solution...
@byronjordan: It's a nice puzzle indeed and you nailed it :-) if you have knowledge of logic circuits finding the puzzle would become much easier. But you are right, if the person asked has no logic circuit knowledge, age doesn't matter... good luck with the other ones

That's the solution I know. But the solution you gave is more intuitive, although longer to explain. From a pedagogical perspective, I prefer the first solution you gave. Esthetically, the second solution is better. Cheers!