How Many Plants Can You Grow Without Exhaust?

I need help quick, before i go buy everything today

well, that really depends on your setup.
You would need to explain what type of grow room/tent you are in, what type of lights, what the temps are, etc. exhaust is used to bring fresh air in to an area and to remove bad smells via a carbon filter. You don't really need an exhaust if air flow and smell are not a problem. The only place I could think of is a greenhouse or outdoors.

well ive got about 20x10 ft to work with the the cieling is 7 feet, and im using a 1000w HPS eco light and ive got like three fans set up and theres no windows in the room only a door with two 1x1ft vents on the top and bottom. im probably gonna grow six plants at a time, should i need an exhaust system for that?

If you dont want the house "Reeking of high heaven", then yea.. or atleast thats the general idea! I see going here, if you dont care of the smell, and there are 2 vents then you might not need an exhaust system.

Dont use the whole room, use about 4x4. 6 plants is a good number, veg for about a month maybe longer. Your going to want to exhaust the heat out of the room, 1k produces alot heat. Or you can do a sealed room and have no exhaust but then youll need to supp co2