684 UK tablespoons in US gallons
Conversion
684 UK tablespoons is equivalent to 2.7104052571946 US gallons.[1]
Conversion formula
How to convert 684 UK tablespoons to US gallons?
We know (by definition) that:
We can set up a proportion to solve for the number of US gallons.
Now, we cross multiply to solve for our unknown :
Conclusion:

Conversion in the opposite direction
The inverse of the conversion factor is that 1 US gallon is equal to 0.368948516959064 times 684 UK tablespoons.
It can also be expressed as: 684 UK tablespoons is equal to US gallons.
Approximation
An approximate numerical result would be: six hundred and eighty-four UK tablespoons is about two point seven one US gallons, or alternatively, a US gallon is about zero point three seven times six hundred and eighty-four UK tablespoons.
Footnotes
[1] The precision is 15 significant digits (fourteen digits to the right of the decimal point).
Results may contain small errors due to the use of floating point arithmetic.