1. Each of the boys has his own computer.
2. Each of the boy has his own computer.
3. Each of the boys has its own computer.
4. Each boy has his own computer.
(Is #2 wrong? Are all of them except #2 correct and the same?)
1 and 4 are correct; 2 and 4 are incorrect.
The problem in 2 is "boy" and the problem in 3 is "its."