Title says it all. Would love to know.

Your save file will tell you how long you've played for your character, or do you mean across all characters?

Save file would tell you how much. Once your done with that save file, write down the amount of hours somewhere so that you can keep track. I didn't do that but I have a good idea on the estimate of how many hours I've played.

Is this a joke?

No. I noticed the PC version gave an all-round figure of the all hours put in. I wondered if the option was there for 360. Why would I bother making a topic as a joke? I'm not 12.

Just make a guess. +/- 500 hours and you should be pretty close.

Join raptr.com and sync your accounts. This also works for Steam and PSN.

http://raptr.com/

That is rather rude. OP asked a simple question with a simple answer. Sorry not everyone is as smart as you.

It involves an highly advanced equation of adding together each of your different character's game save with the highest time on it.