Carbon dioxide found in hot springs this year

If we start with 1000 cubic feet of natural gas (and assuming it is pure methane or CH4) at STP (standard temperature and pressure, i.e., temperature of 273°K = 0°C = 32°F and pressure of 1 atm = 14.7 psia = 760 torr), and burn it completely, here's what we come up with:

1 cubic foot (cf) = 0.0283165 cubic meters (m3)

and 1 m3 = 1000 liters (L)

so 1 cf = 28.31685 L

and 1000 cf = 28316.85 L

Since 1 mole of a gas occupies 22.4 L at STP, 28316.85 L of CH4 contains 28316.85/22.4 = ...