What fastlane says is true, the one quant = one inch is just given to you to give people an answer to the question, it does not need to be an inch, if I told you it was one foot it would not make -386 quants/^2 any different. In short the size of a quant does not matter.

However if you were wondering -9.81 m/s^2 is the acceleration due to gravity, which is a constant near the surface of the earth.. (calculation by Gm/r^2)