room dimension 40x20x10m does that = 8000m3 to convert 8000m3 to litres do I multiply 8000x1000

litres and meters are different measurements. 1cc = 1 mL. I would suggest you convert the initial dimensions to centimeters. So that when you get the volume, it would be in cubic centimeters. And 1 cubic centimeter is 1 milliliter. 1000 milliliters in one liter