[marebare]

1 mile = 1.61 km
radius of the world = 7960 miles
surface area o a shere is 4pie r2
so the surface area of the earth is

4x3.14x7960(2)=316.27 miles or 272.64 km

is this correct

[Borek]

is this correct

Unfortunately - no. 7960 miles is diameter, not radius. And your result should be is square miles/square kilometers. And much, much larger. And your convertion of square miles to square kilometers is wrong as well

[Martingale]

Also, once you fix your calculations, your answer will probably be off by a nice amount since the earth is not a sphere.  It is an ellipsoid.

[Borek]

Also, once you fix your calculations, your answer will probably be off by a nice amount since the earth is not a sphere.  It is an ellipsoid.

Yep. But that will be the least of her problems.

http://en.wikipedia.org/wiki/Earth

Use mean radius.