How many Gallons can you get from a gallon of water?

It's about 2000.

2.125 gallons.

1000000 gallons 10^6

I take it you mean "how many drops of water in a gallon"? :))

A gallon of water weighs about 8 pounds. You might want to remember the rhyme: " A pint is a pound the world around." (although that only applies to water) and that there are 8 pints in a gallon.