I am adrift. I'm taking inventory of my stock. How long will my reserves last? I have a liter of Paddy's whiskey, a liter of Osborne's Veterano brandy, and a fifth of Black Velvet. I'd rather not drink the latter. I have some Rich and Rare also, but I'd rather not drink that as it is more a mixing whiskey than a sipping whiskey.
Like a castaway I am assessing my rations, calculating my intake, multiplying by amount, and coming up with a calendar. How long will I last? Mister Booze won't be buying any booze for probably a month. Mister Booze hasn't bought any booze for the last month. Mister Booze might have to go month after that without buying any booze.
If my supplies run out, what shall become of me? How long can I last?