Calculating Local Gravity: How is g = 9.81m/s^2?

[Kat007]

Homework Statement

I am wondering how did the local graviational field (free fall acceleration) g = 9.81m/s^2 is calculated?

Homework Equations

The Attempt at a Solution

 

[kuruman]

It is usually calculated by assuming that the Earth is a perfect sphere and then by using Newton's law of universal gravitation to find the force on an object at the surface of the Earth. Input parameters are the gravitational constant and the radius and mass of the Earth.

 

[Kat007]

So what is the actual equation used to obtain the g (with the values)?
Just out of general interest.

 

[kuruman]

$$G\frac{M_E\:m}{R_E^2}=mg$$

Solve for g.

 

[Kat007]

OK thank you for your time.
:)