How many kegs to buy for 100 people?

and about 70 people will drink beer. I wanna supply at least 6 beers per person (the bottle kind). I guess that 450 beers I would need to buy. Is this enough for one keg? 1/2 keg correct? I'm not a beer drinker so I'm not sure how many it takes to get drunk or if keg beer taste bad. I'm also going to have fruity girl drinks and shots. So I don't want to have tooo much.