Four.
128 fl oz = 1 gallon 2 x 128 fl oz = 256 fl oz = 2 gallons 4 x 128 fl oz = 512 fl oz = 4 gallons
128 fl oz
101.44
128 fl oz in a US gallon.
1 US gallon = 128 US fluid ounces
128 fl oz(US) = 3.78541 L
As a very wild guess I suggest it might be close to around 128!
There are 32 fl oz in a qt. This means that there are 5 qts in 160 fl oz.
(480 fl oz) / (128 fl oz per gallon) = 3.75gallons
(2 gallins) x (128 fl oz per gallin) = 256 fl oz
16 qts
There are 128 oz per gallon (16 * 2 * 4) = 128. 100/128 = 0.78125 gal