"fred" wrote in message
...


Are they rewriting math rules now? ... negation is different from
subtracting? Indeed! Not in any math book I've ever seen.


This is an interesting point.

I guess I tend to view the two things as being separate and different
in nature.

Negation (in the sense that I believe you are using it above) such as
turning +5 into -5 'creates' a new number. The value of that number
is -5.

Subtraction is an operation performed on one value with another.
Therefore, subtracting +5 from a value is a different thing.

I guess where this becomes important is in the example used elsewhere
in this thread of:

=-5^2

It could be argued that it is quite valid for either answer (+25
or -25) to be correct depending on whether we are squaring -5 or
whether we are (implicitly) subtracting 5^2 from (the implicit) 0 that
is not shown.

If we put the zero in:

=0-5^2

then I would suggest that the *only* valid interpretation is that we
are subtracting 5^2 from zero, and thus the answer *must* be -25.

Given that excel must have rules, it does not seem unreasonable for
the algorithms to require an explicit subtraction, else go with the
interpretation that we are squaring -5.


Having said all of that, if we don't bother to use brackets to make
the calculations completely explicit and unambiguous, then I guess we
are each *choosing* to take the risk - whether we know it or not.

Does my thinking sound reasonable?


Alan.