The most interesting way to write 6 billion is in scientific notation. In scientific notation, 6 billion would be written as 6.0 x 10^9. I personally believe so since scientific notation is important in ways of shortening lengthy numbers when writing. Though this is mostly for scientists to use, I find it fun to convert from standard form to scientific notation!
Answer: The data cannot be modeled by an exponential function because the data is for a linear function (as there is a constant increase in f(x) each time x increases by 1)
