What is 5.009 as a fraction?

5.009 as a fraction is 5 9/1000

I'm here with a simple explanation:

Any number before the decimal point is a whole number.

So 5 is the whole number in the fraction.

Now to determine 0.009 as a fraction,

9 is the numerator.

Count the decimal point as 1, count 009 as zeros; 000. This automatically makes 1000 the denominator.