[Fsf-friends] [OT]Notations for representing infinity

[Richard Stallman]

    > If I remember my math, division by zero is properly said to be
    > indeterminate, and not infinity. Infinity is not a number, but a concept
    > -- if that does make sense.

It doesn't make sense because it is a garbled version of a more
precise statement that does make sense.

To say that something "is not a number" has no precise meaning.  To
give it a precise meaning, you have to say which kind of number you
are talking about.  Mathematicians use various systems of numbers, and
some of these systems include infinite numbers.