Q: The world currently uses up ≅85 million barrels of oil per day. If the total remaining oil reserves ≅ 1 trillion barrels, how many more years do we have before we run out?

Typical A:

(85,000,000 barrels/day) * (365 days/yr) = 31.025 billion bbl/yr

1 trillion bbl ÷ 31.025 billion bbl/yr ≅ 32 years, 3 months

Notice any problems with the ("mathematically correct") answer?

Even putting aside,

#0 The above assumes usage/demand does not increase..
#1 Environmental reasons not to burn..
#2 Is it energy-policy-wise to burn all, so none is left?
#3 Is it practical or realistic to go from 85 mbd one year, to zero the next?

#4 Physical reality of oil fields.

Geology says:

Oil fields ≠ a gas tank