I like you found it really hard at first visualising and then coming up with a ratio as everyone sees colours differently it alright saying pale yellow use this formula, orange use this one so having names and coming on here has really helped! With practice i got there sometimes I still doubt my self and go over things about a 1000 times in my head.
With kadus if it's the same numbering system as wella take a look at this thread
http://www.salongeek.com/threads/wella-thread.285086/
Really helpful for all info regarding tones and colours!
Also
@cassies97 is the wella geek and the go to if you have any queries I personally think there's not a question she can't answer in regards to wella!
Really don't let this knock your confidence everyone here is willing to help anyone that is egear to learn and has their own ideas about how to approach it may it be wrong or heading in the right direction it's all about learning about new things and also where you've gone wrong. I don't think even the best hairdressers can say they still aren't learning new things!