I'd like to count the number of values that a user enters in an excel simple
addition calculation.

For example, if the cell has "=17+256", I'd like to get the count of "2".
If the cell has "=101+2+0+65", I'd like to get the count of "4". Is there a
way to parse this 'function' string?

Everything I've tried so far starts *after* the cell value has been
calculated (e.g. it's working with a single value of 273 and a single value
of 168 for the two examples above, respectively).

Thanks,
- Cathy