I'm reading the planetary economy rules, and some things seem a bit odd.

Firstly, on the civilization level calculations, it says Planet Surface Area, or PSA for short, is Planet Area times 222. Where does the figure 222 come from? A city, with the surrounding unbuildable area included, is 22^2 squares large, that's 484 squares. The concerning example first calculates PSA = 4 * 222 = 888, but in the end uses the figure 1936 where that 888 should be. 1936 is 4 * 484, though.

Secondly, in all of the Sum of EachN/Sum of EachM calculations, it is possible that no facility from the EachM list is present. What sort of methods are used to prevent divide by zero errors in these cases?

I'm not going to be building tax planets, just curious.

Firstly, on the civilization level calculations, it says Planet Surface Area, or PSA for short, is Planet Area times 222. Where does the figure 222 come from? A city, with the surrounding unbuildable area included, is 22^2 squares large, that's 484 squares. The concerning example first calculates PSA = 4 * 222 = 888, but in the end uses the figure 1936 where that 888 should be. 1936 is 4 * 484, though.

Secondly, in all of the Sum of EachN/Sum of EachM calculations, it is possible that no facility from the EachM list is present. What sort of methods are used to prevent divide by zero errors in these cases?

I'm not going to be building tax planets, just curious.