I wish to change the number of displayed decimals in a table based upon a
single cell entry, i.e. "enter number of decimals" and change the table
accordingly.
Conditionally formatting does not extend to number format.
Format painter will not update unless you repeat the entire process.

Is there a relatively simple way to change this, other than the classic method
of INT(formula value*10 or 100, etc.)/((power of 10) that could be applied
to a series of linked tables?

(--many, many cells would have to be modified)