I think he just tries to act stupid so Moriarty won't think he knows that he is going to "die" Sherlock had a plan, and if Moriarty knew that, he probably would have killed Sherlock himself or made sure that he actually died.

I think the moment Sherlock knew he was going to have to "die" right after the scene with Richard Brook. Him and John were outside and Sherlock says something like he knows what he has to do...then he was acting stupid all through the roof scene to try and fool Moriarty...although I think he was still genuinely surprised when he shot himself!

But d'you think he already knew about the 3 assassins before Jim told him??

Yeah, I think he knew about the assasins before Jim told him too...he's too smart, he would have worked that out already - he knew there were assasins living in Baker Street and he also knew that Moriarty has used assasins before (in pool scene in Great Game)...

Davina wrote:

Early in the episode Sherlock goes onto his computer and it lists the assassins and he says they have him under surveillance. In fact I'm pretty sure there are 5 names listed. Mycroft says there are 4 assassins. Once 2 are dead then that should have left 2 still operating but Sherlock knows there are 3 still operating.

Sherlock knows, because Moriarty told him, that if he did not stop interfering with Moriarty's activities Moriarty would 'burn him' and yet Sherlock deliberately interfered and got lots of publicity as a result. Sherlock is not stupid so this must be calculated.

No, the fifth one we see on the 'network places' window would be his own. (check on your own computer, yours is listed) The other 4 are the foreign assassins.

Moriarty has a huge network of criminals at his disposal.
The 4 he enlisted to 'get Sherlock' were all trying to get the keycode from him. I doubt they would then be the ones waiting & watching to see if he dies, the 2 remaining ones want him alive!
The assassins in the end scenes were paid to kill the 3 friends. There is nothing to suggest they are the same assassins as the other 4 foreign ones.

The other thing that has just stuck me as being out of character for Sherlock is about the code that Moriarty taps out. It is unlike Sherlock to just accept that a code exists. The conversation with Moriarty in the flat, when they are drinking tea,  has Moriarty feeding conclusions about a code to Sherlock. Sherlock is not stupid and her knows that everything Moriarty does and says is done for a reason. Why did Moriarty come to the flat? It wasn't just to gloat over having escaped imprisonment. Sherlock is not actually very surprised that he has got off, is he. Clearly his visit is vital for the game to move on.

If Sherlock thought that he had 'discovered' the code that Moriarty had tapped out- why- then surely Serlock, who never accepts anything on face value and only accepts facts and makes deductions from them, would have tested the code to see if it worked. That would not be beyond his capabilities. He may possibly have involved Mycroft in this. He says earlier in the episode, when he and John are running away handcuffed together, that this is not the time for a reconciliation with his brother. Perhaps after the Richard Brook incident he decides it is time to involve Mycroft after all.

Just thinking you know.