Problem of the Week Problem E How Many?

Natalia has a jar containing some number magnets. In the jar there is one set of numbers from $$1$$ to $$9$$, as well as some extra number $$5$$ magnets and number $$8$$ magnets. If the mean (average) of all the numbers in the jar is $$6.4$$, what is the smallest possible number of number magnets in the jar?