One division is ten percent. You'll just have to imagine this in terms of tens going by. Must be some old Japanese percentage system that carried over or something. Just remember that one wari is ten percent, two waris are twenty percent, and so on.
The readings are the same as what you learned with the kanji. You know much more than ten percent of this word's reading already.
When I write an article, I have someone check it for me when it is about ten percent complete.
The number of Christians in Japan doesn't even reach 10%.
"This blowfish is a bit too expensive. Could you give me a discount?" "I’ll give you a 10% discount."