I did do the math. At 1.5 oz, there are 85 shots in a gallon. 85 * 4 gallons = 340 shots. 340 /.40 (80 proof alcohol) = 850 850/365 = ~2.3 shots of 40% alcohol. But then 1.5 oz shot is pretty small and my knob Creek is 50% :)

Edit: so it's 3.5 oz, not shots. Also, mmmmm whiskey.