"It takes nine days."
I wish it read the kanji out especially for dates. There are some special rules with how you pronounce numbers of days! This page has a good section on it: http://www.guidetojapanese.org/learn/grammar/numbers
I get where you're coming from, but this sort of thing will end up teaching you more. Though I understand the frustration. It is correct that 九 and 日 separately are きゅう and にち, respectively, but together 九日 is ここのか. It's just one of those weird things languages have. English has just as many, I assure you.
Knowing how different kanji sound/what they mean by themselves as well how they are together will keep you streets ahead. That way you have some knowledge base if you find a new word that uses a kanji you already know. You might even be able to guess the meaning of new words like that once you know enough. Avoiding that frustration you're feeling will just leave you streets behind.