[buro9]

Area of a 10km circle is 314 km2

Area of a 20km circle is 1257 km2

Assuming they go to 30km or 50km next:

Area of a 30km circle is 2827 km2

Area of a 50km circle is 7854 km2

[mistermann]

I have a feeling most people on HN know how to calculate the area of a circle. ;)

[Retric]

<pedantic> True, but calculating the land area by doing so is a mistake because ~50% of that 20KM circle is over the ocean.</pedantic> http://maps.google.com/maps?hl=en&biw=864&bih=471&#3...

[rphlx]

Should we count lakes and other self-contained bodies of water on land?