If your home requires 2 million Btu of heat energy from the furnace what is the cost in dollars to heat the house with natural gas assuming 60 percent furnace efficiency?

If your home actually requires the 2MM btu then that is the output you need, if your furnace is 60% efficient then you would need 3,333,333 btu input to produce 2,000,000 btu output, There are 1000 btu per cubic foot of natural gas therfore you would burn 3333 cubic feet of gas to produce 2MM btu. Your question cannot be answered here because I dont know what you pay per cubic foot of ng nor did you give a time frame for how long you plan on heating the house. But now you know the figures and you can do the math.