How to update iPhone 3 to version 4.3?

I have the iPhone 3, version 3.1 (8B117) and was wondering if I could update it to 4.3 at least because a lot of the apps that I try to download require that update. Can someone tell me how to do this in the simplest way possible?

Via OTA Update Via itunes… Or Google it.U vcan Find Better more ans which is easier to you.

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If your iphone is 3g then it is impossible to upgrade to 4.3.