i just got interested in pokemon and wanted to know what is the damage calculation for a critical hit (i.e. 1.5x) and is crit random and if not what do i need to do to get, srry again for such a noob question but i am;)

That was a mouthful...

Critical hits are best described as random, but some moves have a higher rating of critical hits. And then there is Focus Energy. That move raises the chance of getting critical hits. And then there are times, like the Scope Lens, which also raises the critical hit percentage for the Pokemon using it.

There are several Pokemon that can combine these things to create a critical moveset.

Take Blaziken for example

Blaziken@Scope Lens
Focus Energy
Blaze Kick
Slash
Sky Uppercut

This moveset takes advantage of critical hits. Use Focus Energy, then the other three moves have a higher critical hit percentage than other moves. Add the Scope Lens, and you'll probably get a critical hit every other hit.

But yes, Critical Hits are pretty much luck.

ok, thank you for that, but may i also ask what the damage calculation or multiplier is?

The multiplier is times two, like a super effective attack.