Why does Max do this at the end of Pi?

It is the only way he sees to safe his life.

It is strongly implied that the mystical 216-digit number that Max was researching has a devastating effect on whatever comes into contact with it.

• Max's computer crashes pretty violently at the two occasions when it computes the number.
• When Max tries to write down the number after his computer crashes the second time, he passes out. His abilities to foresee the stock market numbers after that imply that the contact with the number has transformed his brain in some way.
• Sol's death might have been caused by the number. The notes that Max finds in Sol's apartment after his death imply that the conversation with Max has inspired Sol to resume his previously abandoned research of the number. It is reasonable for Max to believe Sol might have discovered the number and the effect of the discovery caused the stroke that killed him.

Max's dilemma now is that by the end of the movie, he realizes that he does not want the knowledge about the number. He knows that people will not stop pressing him into revealing the secret of the number, but he also has reason to believe that the number is too dangerous to share its secrets with anyone, let alone the shady characters that he met during the movie. But how do you forget something that you have learned? How do you un-know something?

The only way he sees is to remove the part of his brain that contains the knowledge of the number. This also robs him of his mathematical skills as collateral damage, but the smile on his face in the final scene, where he cannot solve the math problem that his young neighbor asks him, suggests that he gladly accepts that as the price to get rid of the knowledge of the number.

Is Max aware that drilling into his skull might kill him? Probably. But at this point he is desperate, and might prefer death to the life that he sees for himself if he keeps the knowledge of the number.

Does the number really have those effects or is it all in Max's head? We don't know. The movie is told through Max's eyes, so large parts of the narration cannot be trusted. It could very well be that the events of the film were just a chain of coincidences, and Max's obsession with patterns led him to believe that they were connected by the magical number (which is exactly what Sol suggests in their discussions). Maybe he was even mentally insane. In this interpretation, drilling into his brain removed the part that caused his obsession/insanity. The movie is deliberately ambiguous in this regard, so both interpretations seem valid.

He realises the number is dangerous. Not only can it be used to manipulate the stock market (all economy) it can also be used for religious purposes, making people fight one another. So, this is the only way he can remove the answer from ever being discovered / taken out of him.

For me, max is, as Euclid, a computer. Hence, he kills a lot of bugs during the movie - even once, the phone stop ringing when the bug appears. Like someone wanted to interact with the said computer but the bug stopped that. More, Jenna, the kid, is a "test program" to know if the computer is still working correctly on simple problems. More, Max is name "Icarus" by "Sol". All computers have a antique name, I think Max's computer name is Icarus and Sol is another computer with which he is interfaced. Now the Kabbalah and the Wall Street guys: they are programs that will try to force to have the figures with hostility or frienship. The movie is shot in black and white : 0 and 1 in the head of Max. Other things, the landlord saying "you do not have right to install locks" : the computer cannot protect itself from the human with its own lock. Every time he is close to find the figure : his neighboor tries to stop him, then he does it anyway and he has a massive headache. Like a computer trying to reach a result that asks to much of its power.

The end : Sol dies after writing the figures - as every other computers. Max finds the figures and starts to spell them out, we can see he goes all blank, more and more blank ==> Goes to the infinite 0 ==> dies. He returns and drill his head but he's still alive : he removes his capacity to do math. Thus, when Jenna tries the simple test program, he does not know the answer.

Last question : who is his neighboor, the girl ? Either a friendly user who is trying to help or a self defence program he/it created.

I felt that this movie is much more of a reminisce standpoint. The scar on his forehead being that of the drilling he did as it ended. So when he saw it he is shocked and goes through memory repacking. By the end he remembers what happened but he has gotten rid of the number so he is happy with giving up his mathematical prowess. As a fact of looking at the sun i thought it was more on the effect that he defies the normal order of things reason as to why he would never have stopped looking for the pattern. The dead brain he kept seeing were the part of his memory that he has forgotten that had left little trails that were leading him to recovery of memory after drilling his head.

Its a movie about complex numbers that overwhelms the brain/system

If wall street peoples know it they can crash the market ; If Jews know it they can ask wishes from God(?); But the numbers & patterns are so phantom that we(Humans, computers) cannot comprehend it and thats what the movie is all about it, the computer cannot process it, the jews cannot acquire it, the protagonist himself and his teacher goes critically ill (Burned out).

This guy Guillame(https://movies.stackexchange.com/users/44031/guillaume) explains that Max himself is like a computer and I couldnt agree better cos at the end as he is getting burned up(over processed),he gets more bugs (ants, hallucination, pain etc) he burns his chip(brain) until he has to be replaced where he just forget the math the kid asks him then he would again gain all knowledge of math only to get burned again and plot/ process repeats again and again….

Fibonacci Sequence results in shape and solving pi results in shape/pattern as well and it is overwhelmingly complex pattern that it repeats itself so much that it pushes the processing limits to oblivion so even if you find the numbers its not as impossible as FINDING THE PATTERN/MEANING where the actual problem lies causing brain/system to overload to death…

TLDR: As he solves it the more overwhelmed, burned out he becomes until he is REPLACED(Max alive/better/replaced after drilling himself(climax)) and restarted(forgets maths and will be taught) again and again…..