For in a sentence I needed te て-form of 知る (知って, now I know it), but I just happened to forget how to conjugate it. I just remembered seeing some kind of conjugation table for specific verbs, but I have no clue where to find it. In case you don't know what I'm talking about, I remember it looked a bit like this:
Pull up the dictionary entry and tap/click on the "Godan verb..." part.
Keep in mind that these tables are, as far as I know, automatically generated and sometimes contain mistakes. For example the table for いらっしゃる is way off.
PS: They're generally reliable for regular verbs, but shouldn't be trusted blindly.
