Whether or not you close cards is for you to determine using the information below along with your needs, wants, priorities, goals, preferences, etc. There is not a yes or no answer that applies to all cases.
This thread is linked in the Helpful Threads sticky in the Credit Cards subforum:
http://ficoforums.myfico.com/fico/board/message?board.id=creditcard&thread.id=117125&jump=true
Scoring factors are covered here:
http://www.myfico.com/crediteducation/whatsinyourscore.aspx
Number of cards is a common topic. It's not the number of cards that matter as far as your score is concerned. It's more a matter of your specific needs/wants and what you can responsibly manage. You can also refer to:
https://www.google.com/search?q=number+of+cards+site%3Aficoforums.myfico.com&oq=number+&aqs=chrome.0...
