Separating a numeric field

[BTate]

I have got a Numeric field that Changes:

I want to separate the field:

E.g. the field starts 123
next 123.4
next 123.4.1

I want to create a column using a formula e.g. a select statement that distinguishes these extensions.

Thank-you
Bryan

 

[idle]

A numeric field cannot have the format 123.4.1.
Could you clarify whether the data with the changes is stored in a single field in a single record, or in multiple fields in single record, or in a single field in multiple records?