How many Credit Cards should I have open at one time?

Right now I have 10 Credit accounts open. Ranges from 4.00 to 00.00 with a credit score of 728. I have {content} balance all of my cards at this time. I just applied to get a motorcycle and they denied me saying that I have too much revolved credit open. I rent a apt due [...] http://bit.ly/kuD7Df