Why Prophet Muhammad married more than four women as permitted in religion?

Answer 1

He did not marry all of his wives at the same time. But he did exceed the max number of 4 because he is a Prophet and he would surround himself with more life partners to memorize the Hadeeth and his acts to benefit Muslims. He also used Marriage to create alliances between different tribes and parts of the land and to help him spread Islam and piece instead of the civil wars that were going on.

Right....! Above sister lilly said truth....

He removed many old customs by marrying with different tribes and different races....

Islâm as the perfect religion is both rational and practical. The Prophet's plural marriages, which exceeded the maximum number allowed for men is an exception to the Qur'ânic injunction (i.e., 4:3) to show all possible types of marriages in Islâm.

The fact that he married Khadijah bint Khuwailid (may Allah be pleased with her) and lived a monogamous life for twenty-seven years till Khadijah died

But his marriage to Khadijah shows only limited types of marriage that are allowed in Islâm. That is, it is permissible for a man to marry a woman who is older than him, for a poor and orphan man to marry a wealthy woman, for an employee to marry his employer, and for a bachelor man to marry a widow.

If Allâh the Most Merciful did not allow the Prophet (PBUH) to marry other women, how could marriage in Islâm be open to all other types of marriages?

so, He married more than 4 for many reasons...! for full details you can visit this link to know more...

http://islamgreatreligion.wordpress.com/2010/09/20/the-wisdom-behind-prophet-muhammads-saw-plural-marriages/

also in the Qur'an it also says a man is aloud to marry 4 wives at a time because the women population it more then the man population, as long as the man treats each women with the same respect and spends the same time with each one (which would be very hard)

hope i helped