How much propane gas does a residential oven consume on average? (in US Gallons)?

The normal usage for an oven at 350 degrees for 60 minutes is about .45 gallon and 4 times a week times .45 would be 1.80 gallons a month. You mentioned a 100 gallon tank? I think you are referring to a 100lb tank. If the tank is not setting on blocks in the yard and it's standing by the home, they are by the pound. Like the one you use with the grill. It is a 20 pounder. Ect.