Here is the basis for this question.
Income = FIM x PIM x 350 x TSM x SBR x RAND
Income from a facility has everything nicely multiplying. Sustainable Business Restrictions (SBR) = 1 unless you have more facilities of a type than you can support. SO logically the SBR should be less than 1 when having more facilities than you can support for the equation to make sense, otherwise you'd be gaining money.

But I can't work out the formula so that SBR ends up being less than 1. Pasted straight from the rules

((Planet Size in Squares) x Civ Level x MNSF) / (0.85 x RNF)

Planet Size in Squares: for a 20x20 planet this is 400

Civ Level: as used everywhere else

MNSF: max number of sustainable facilities (of that type) per city

RNF: real number of facilities of each type

0.85 comes from the fact that the CL cannot exceed 0.85

so a 16x16 (256) civ level of 1.74% (.0174) x 4 offices / 0.85 x real # of say... 5 offices

which gets me ((17.8176) / (4.25) which is by far larger than 1.
So I don't get it. having 1 more office than sustainable shouldn't let me multiple money earned by 4x

So what I can't figure out is where I am wrong. Is my logic wrong? Is the MNSF not a whole number but some sort of % or decimal?
Is the equation actually backwards so it would be 4.25/17.8176 since that gets me a smaller number than 1?

With a size of 256, a civ of .0174, 4 offices per city, you would need to have at least 22 offices on the planet to create a SBR less than 1.

Maybe the SBR only comes into effect WHEN it is less than 1. The rules do say " Therefore, the maximum total income per facility type is divided between all of the facilities of that type if the number of that type of facilities exceeds the maximum sustainable number." It says IF. It must have something to do with the civ level as well, since your 16 x 16 planet has approximately 2,155 squares covered by facilities if you have a 0.0174 CL.

Okay this makes sense to me. I think the error is in my own logic.
I was under the impression that the MNSF is linked to the number of slabs you have currently built as has been mentioned to me.
But the rules specifically state:
The market changes as more facilities get built. To reflect this, the maximum is linked to the civilization level (CL) of the planet.

I think I just stopped reading when it got to the previous sentence about losses, and since I didn't care about loses I didn't get that important bit.

MNSF has nothing to do with the number of cities you've got, it is just a matter of Civ Level.
A 16x16 with a just about nothing on it like civ level of 0.24% (0.0024 CL) can according to math support 3.4 Offices and not 4.

MNSF is only taken into account when the # of facilities built > the number of cities built * the MNSF number of that facility. So it does matter how many cities you have, in a sense.

Can I request the rules be updated in the Rules Update forum with this information then?
It seems like it would be good to list all of the rules regarding MNSF with the rules about MNSF so that future peoples don't run into the same troubles.