Play the game
Actually, I'd submit the answer is in the last sentence by Willit Run.
Anyone remember Tom Cook from Southern and Atlas?
When I flew with him he'd make a game out of guessing the V2 speed and the Stab Trim Setting.
I'll be damned if he couldn't guess it within one knot and one tenth of a unit on every flight just by looking at the weight and CG.
Like the man said, look at it and ask yourself, does it look reasonable?
Thanks for teaching me the game, Tom.