Forget Keyword Density. Focus on Keyword Frequency
It’s unlikely that Google uses keyword density as a ranking factor.
But there is no doubt in my mind that they look at the number of times a keyword appears on your page.
(Known as “Keyword Frequency”).
Think about it:
Imagine if page A contained the keyword “oatmeal cookies” only once.
And page B contained that same keyword 7 times. Which page would you think is more likely to be about “oatmeal cookies”? Thought so.
Bottom line: Use your target keyword at least a few times in the body of your article.