If a scientist has two empty breakers that he needs to fill with a certain chemical a three gallon beaker and a five gallon beaker. How can he measure exactly one gallon of the chemical without wasting any?
He could use the measurements on the sides of the beakers. Most have them. If there are no measurements, measure it into thirds or fifths. Unless you mean something else
He could pour the 5 gallon breaker into the 2 to be left with 3 gallons. He can pour the 2 gallon one out and pour the 5 gallon one into the 2 gallon one again to be left with 1 gallon.
