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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?