Base Stats are a Complete Mess

I'm at a loss for words. I realize this game is called LoL and damage calculations are probably an uncomfortable topic, but base stats for a champion should be simple and 100% accurate.

For example, Vayne begins with 498.44 health at level 1 and according to her official page she gains 83 health per level. If I go into a custom game with no runes, no masteries and no items, I expect each levels stats to tie in with the stats per level chart I made. But it's not even close; none of the stats are. Completely inaccurate and inconsistent changes per level as well. How am I supposed to know how many 8 health seals to buy when the base health stat can be off by 100 at any given time?

Excuse my language, but what the F@CK is going on here? Not to mention that even the calculations for the scaling runes are often inaccurate (i.e. the change per level doesn't tie into the sum when you multiply it by 18). Is this supposed to be some sort of joke? With these kind of errors, it leaves me wondering what are the most up-to-date figures and what are they supposed to be.

Here's my solution: Be straight up with us Riot. Stop f@cking us around with simple addition and multiplication errors. I could probably go into your place of work and fix the myriad of inconsistencies in a week. Start with fixing base stats, then move forwards.