* Convert gallons to milliliters: 1 gallon is equal to 3785.41 ml.

* Calculate half a gallon: Half a gallon is 3785.41 ml / 2 = 1892.71 ml

* Divide by 750 ml: 1892.71 ml / 750 ml/bottle = 2.52 bottles

Therefore, there are approximately 2.52 bottles of 750 ml in half a gallon.