Smoke alarms in rentals

How many smoke alarms do all you landlords out there put in each home you are selling or renting? Does it depend on how many bedrooms there are?
Where do you locate them at?
Also do you use carbon monoxide alarms? If so, how many and where do you locate them?
Thank you all!

Find out what state and local code says!

My insurance agent tells me one is minimum, but more are recommended - it could vary by state. I put one just outside each bedroom and another in the kitchen.

I have not put a CO alarm in any of mine up to this point, but the risk is minimal since they are all electric units. If they had gas / propane service I would probably just buy the fire alarm CO combo kits and apply the same way.

If you are renting them this gives you an opportunity to inspect the homes at least 2 times a year to make sure the alarms are working and the batteries are in good order. The number of detectors gives you more range in the home to inspect them and see if the home is suffering damage from the tenant.