The equation of a linear function<span> has no exponents higher than 1, and the graph of a </span>linear function<span> is a straight line. The equation of a </span>nonlinear function<span> has at least one exponent higher than 1, and the graph of a </span>nonlinear function<span> is a curved line.</span>
A linear function has a constant additive rate of change, while a nonlinear function does not. For a table of values to be linear, the dependent variable must have a constant rate of change as the independent variable increases by 1. On a graph, the function must be a straight line to be linear.
You could estimate by doing 600x3=1800 (becasuse of the 0's in 600 it is easier to do 6*3=18 and then add two 0's to the end 1800) then you simply multiple 640x3=1920
