[sicxu]

Just cover the continent will require a lot of balloons. The world has 148,429,000 sq km. If you cover 1600 sq km per balloon, that is 92768 balloons. Just cover Africa will require around 20k balloons. It will only work out, if Google can increase the coverage area per balloon.

[gaadd33]

20K ballons doesn't seem like that many unless each one costs a ton of money. From an industrial production point of view it barely seems like a drop in the bucket given how many cars/phones/planes we produce.

[mtdewcmu]

Each balloon would cover a circle, so it'd be more like 1,250 sq km. I think it would be optimistic to expect each balloon to cover exactly that area. They'd need to overlap just to eliminate gaps, and I'm sure there's a random element to their motion, so that would require them to overlap more.