Bro, first of all, this is Math, not semantics.
Secondly, to you, that's a big deal. To me, I could understand where he is coming from in the year 2000 when I was in Class 5.
Thirdly, though I understood his point,
game over still wasn't right. He was trying to give the average distance from the center of a compact area of 600 sq. km (Actual area is 696 sq.km) to the edges. If you are a Mathmatician, you'll understand that the square root does not give you the average distance from the center of a compact area to the edges, the more accurate figure is the radius in which case you'll find the square root of the area divided by π.
Thus R = √(696/π)
= 14.9
Thus the average distance from Nairobi CBD to the edge of the city boundaries is approx. 15km
Bro, which schools do you people go to?