I have used Excel for over 10 years and have never encountered this
before.

When I type in a very simple formula, "+28933/6" the formula converts
to a value and will not hold the formula. In the same cell, if I use
a "=" sign instead of the plus sign, it will stay a formula. I prefer
using a plus sign because it's easier to quickly type.

The cell above and below will accept the + sign and will hold the
formula in tact. Why?

Strange too is if I type in "+36000/6" in this same cell, the formula
stays in tact (converting the plus to an equals sign) but if I type in
"+24000/6" it converts to a value.

Any ideas?