Why there are only three blades in a fan,why not more blades?

It depends on the size of the fan. I own quite a few fans and only one has three blades. Larger fans, as are most in my house, have 5 blades.

Balance my son

I have loads of fans. Not one of them has told me she has blades......

The best ones have no blades at all and work the best! This is the future. Never had anything work as good as this one !

Here's a site that will give you a better understanding of what's going on:

http://allnewscience.blogspot.com/2010/03/why-do-fans-have-three-blades.htm