To amplify the above just a bit.
"Numbers" per se are of value primarily in the design or modification of a stunt ship (most especially if it is "significantly" different from its more or less cut and paste forebears). they are important mostly for insuring that a knowledge-based WAG of a "very likely" ultimate CG location can be part of the planning process and drawing the plan from which the new ship will be constructed. Most important, by far, are the likely location of the CG and, therefore, the best location for the adjustable leadout guides. Also important is planning a location at which (hopefully, modest amounts of) weights can be added if necessary to refine the real world example from the drawing board paper! One thing which might not spring immediately to mind, for instance is the location of leadout holes in the inboard wing ribs and/or the location of the foam spars in a foamy so as not to require unsightly "adjustments to their location" after the 20 point finish is applied.
In the final analysis these "numbers" are needed so as to allow at the flying site minor adjustments to achieve maximum inflight performance most of which will be determined by assessing inflight performance performance and determining the need to alter either CG and/or leadout exit location; done by balancing the ship on your left and right index fingers and determining where the CG is versus where you think it might be better and simultaneously where the leadouts exit in relation to the current CG. We then add or subtract weight as suggested by that test and adjust the leadouts if needed and recheck it: all while balanced on our finger tips. I don't think even Howard or Al probably took their drawing board to the field (although I wouldn't put it past Howie to have taken his lap top!) for trimming flights but rather flew; evaluated; adjusted via finger tip WAG and reflew. All of this is relevant to the discussion of tail volume/CG location/flap size and travel, etc. that has been beaten to death in this and myriad other posts on-line. I think this subject needs a bit of a primer that will hopefully provide basic understanding of what is being discussed...to death
I wish I could remember exactly where (maybe on-line or in one or another magazine) but I once wrote a fairly lengthy piece addressing CG location and tail feathers (think Stab and Elevators). Here's a shortened rehash.
The experiment starts out with, say, a 36"X1/4" steel rod (best choice as its CG will automatically be at 50% of its length) or a straight stick with a CG located at mid length. Throw it or drop it out an upstairs window and note that it will "not" fly straight but flail randomly (about its CG, by the way) and its "landing attitude" will be unpredictable.
Add weight to one end, however, and throw/drop it again and the weighted end will always land first. The more weight the more pronounced the "stabilizing" effect, just like a spear! This illustrates the effects of CG location on the stability "equation". It "wants" to go in one direction. Aha! So that's why we add nose weight!
Next, we can remove the weight (making the rod/stick once again unstable) and, instead add "significant" tail feathers" to it so it looks like an arrow. Once again throw it or drop it out of the window. Voila, the non-feathered end will again repeatedly arrive first, thus illustrating the "neutral point" of the--now, due to its complex structure--vehicle! The drag on the "vehicle" is now behind the CG! The more tail feathers you add the greater will be the degree of stability. In addition, the farther aft you locate the tail-feathers the greater will be the stability (think tail moment "arm").
Combine the weight added to the nose and the tail feathers and you've now replicated an "arrow" which is great if you have a bow or a strong arm with which to launch it. It will not, however, ever win the Walker Cup! For that you now need the last part of a stunt ship; a source of lift. We like to call that a wing and some wings will have a "integral" component we call flaps. Note these are not "separate" elements but part of a single lift structure whose configuration allows its lifting capability to be altered in response to lift needs.
We now have a complete vehicle which can fly and/or (in our case given inflight control capability) maneuver if CG, Lift and Tail feathers are appropriately located.
A final significant factor re lift and stability.
Where the CG is located with respect to the "central location" that LIFT is generated (routinely referred to as the center of lift although the better informed might quibble) is the next most important factor in our ability to do tricks with our aerodynamically stable stunter. If the CG is too far forward we'll have inadequate stabilizer/elevator authority no matter the tail's size or elevator deflection, with which to do our tricks. If the CG is too far aft tricks will be impossible because the vehicle has aerodynamically reverted to its "initial" status (the unstable rod) and is no longer capable of controlled flight let alone maneuver on command.
The point at which the aft motion of CG reaches this state is at or in close vicinity to the NEUTRAL POINT (NP), a less familiar term addressed in a few of the later posts. The NP is the point at which the CG is in the same longitudinal (lengthwise) location as ALL of the aerodynamic forces acting on the entire vehicle. You can throw it now (or attempt to fly it) as hard as you can and the outcome will end up in the trash can. Lacking modern fly-by-wire computerization it isn't going to fly straight and level let alone win the Walker Cup.
This is too long already and I could be writing to an empty auditorium so I'll quit. If anyone is interested in more pontification from a near contemporary of the Wright brothers write a post to that effect.