gravitational field strength of the earth

Hi,

Using the formula g = [itex]\frac{GM}{r²}[/itex] I found 'g' to equal (9.792121683 x 10⁶ [itex]\frac{N}{kg}[/itex])

The value of g is 9.8 [itex]\frac{N}{kg}[/itex]. I am wondering if I made an error in my calculations or if there is a method of simplifying to get 9.8.

Thanks,