It really depends on the context of the question.... What are you looking for? Keyword ideas or meta keywords? If it is keyword ideas then the numbers are limitless, just target as many as possible. Good Luck!
The less amount of meta keywords that you use, the more value it adds to each individual keyword. So use as little as possible, but make sure to cover your main keywords. Good Luck!
To be honest, meta is almost extinct if not already. But if your gona still use it then dont go over 8 keywords in my opinion.
i added 10 meta keywords, what is Keyword ideas? whats the different with meta keywords? how i apply it?
Focusing on meta keywords is a waste of time. It has been about a decade since search engines even used that meta tag.
Maybe for the se's, but for other things, like adsense, if it can still give a hint to serving up appropriate ads then still worth it. I always use meta tags where possible.