The fortwinth is a unit which has the unique characteristic that anything measured in it comes out to 42. Space, Time, Mass, etc. No matter what they measure to in more conventional units, they'll come to 42 fortwinths, and cannot measure to more or less, by definition. The size and meaning of the fortwinth changes to accomodate.
The Fortwinth System makes calculations a breeze, in that 99% of all answers cancel out to 1, 0, infinity, or 42. The use of the fortwinth permits many formerly complex calculations to be carried out without a calculator.
The power of the fortwinth stems from the ease with which other units can be converted to it, and calculations carried out without worry about specific numerical components. Since on many exams the theory is worth 95% of the points, and the actual calculation is only a small part of the total score, presumably the use of fortwinths would allow one to completely throw out the points that are given to small details such as "the right answer", and focus on the really important part, which professors continually assert is the methodology.
An interesting secondary application of the fortwinth was later proposed by Russell Schwartz, and that is international finance. The leap to this new world should have been obvious, since it is one of the few other mathematical systems in the world where the units change value and the amount you have stays the same. Applications in extending the fortwinth out of education and into finance are being investigated.
The single problem with the fortwinth is the difficulty in converting back to more conventional measuring systems.