Derived from equation 12.2.2, the
total number of humanoid civilizations
in the galaxy is the sum of all spectral classes:

N_{HumZivGal}
= ∑ N_{zx}
= A·∑ (F_{x}
· F_{ph}
· F_{k }·
F_{Liz}·
F_{m}) 


13.5.5.1
Equation 

Then the equation can be written like this:
13.5.5.2 Equation 

This results in the number of humanoid civilizations of one
civilization level in the galaxy:
13.5.5.3 Equation 

According to equation 6.2.4, the following probability
for a civilization level can be established :
The total probability results from the sum of the
individual probabilities when a set of civilization
levels is considered.
Technological civilizations are levels 6,
7 and 8, so the probability
of a humanoid technological civilization is:
F_{z} = 14.400/7.301 · (1:36+1:49+1:64)
F_{z}= 405.225/3.218.741 = 1:7,943 ¤ 1:8
F_{z}= 1:8
If you want to know how many humanoid civilizations exist
in total, then you have to look at levels 3  8,
i.e. the human development time. Therefore, the probability
of a humanoid civilization
F_{z} = 14.400/7.301 · (1/9 + 1/16 + 1/25 +
1:36+1:49+1:64)
F_{z}= 0,547,168 = 1:1,82759 ¤ 1:2
F_{z}= 1:2
If you want to know how many humanoid
civilizations and precursors exist in total, then you
have to look at levels 2  8, i.e. the
actual human development time. Therefore, the probability
of a humanoid civilization:
F_{z} = 14.400/7.301 · (1/4 + 1/9 + 1/16 + 1/25
+ 1:36+1:49+1:64)
F_{z}= 1,04025 ¤ 1
F_{z}= 1
It was to be expected that across all levels of
civilization, at least 1 existed, i.e. F_{z}= 1:
So for the number of humanoid civilizations in the
galaxy:
13.5.5.4 Equation 

Adapted to the model used so far:
