What you *haven't* told us is which cells these formulas are in. The error
message is referring to a "Circular Reference", meaning that the formula
contains a reference to the cell it's in. IOW, if you have that first
formula [=B52/12] in cell B52 it will cause that error... At least that's
the most likely cause of the error.
Further, these formulas will not divide a *column* by 12. Each will divide
the content of the specified *cell* by 12. It's irrelevant who "taught" you
this, but you've either been misinformed or have misunderstood.
It's impossible to suggest a fix because you give no idea what you're
attempting to do, what cells the data is in, where you're attempting to do
the division or anything else necessary to offer suggestions. To get a
helpful response to any question there are three keywords that describe what
need be included in your query;
1- Details,
2- Details, &
3- Details.
BTW: Did I fail to mention that you need to include Details?
Regards |:>)
Bob Jones
[MVP] Office:Mac