The formula for calculating the experience
needed for the next level of NQII is as follows:
50 * x^2 † 850x - 900... Where x is the level you will reach next.
For example, if my character is level 23 right now, x will be 24, since it is the level he will reach next.
The equation becomes: 50 * 24^2 † 850*24 - 900.
Plug the numbers in and you get the experience needed for the next level!
Hope this helps! :)