Thank you so much for your reply. I trial/errored 0-11 instead of 0-11% (AKA val*.11) and it seems to be in range of the numbers I expect. The guide DOES describe expected outcomes for primary stats but not for HP/MP so I guess I've had trouble being sure of the results.  
The reason I multiplied by .11 is because the guide specifically says: 
The Difference is then capped between 0 and 11%, and the Stat Gain is looked
up on the following tables:
                      HP                                MP
            Difference   Stat Gain            Difference   Stat Gain
                 0%         40%                    0%         20%
                 1%         50%                    1%         30%
                 2%         50%                    2%         30%
                 3%         60%                    3%         50%
                 4%         70%                    4%         70%
                 5%         80%                    5%         80%
                 6%         90%                    6%         90%
                 7%        100%                    7%        100%
                 8%        110%                    8%        110%
                 9%        120%                    9%        120%
                10%        130%                   10%       140%
                11%        150%                   11%       160%
So I see it is not 0%-11%, but rather 0-11 eh? Perhaps an error in the way the guide was written. C# rounds down after converting floats to ints, basically truncation, I can floor it but no need. That's great, though. It answers another question I had about how frequently I should be turning to floats, so it seems the answer is somewhere along the lines of 'never'?
As for why I'm using Unity, it's just my weapon of choice I guess. I've never developed in any other environments, to my detriment. I'm not making a calculator so much as attempting to faithfully rebuild the opening bombing mission for funzies and also to learn and gain insights from the process overall. I love the game so much, I'd consider my life lived by doing this lol.