Are all the numbers the same length? If so, try putting the comma in quotation marks as in: "," under Format Cells CUSTOM (I assume you already know the "Create or delete a custom number format" procedure).
In other words, your custom format would look like:
However, shorter numbers will have leading comma's and larger numbers will revert back to norm.
Sorry, not really a solution, more of a "work around"- it is an interesting problem- I would be interested in how it is best solved.
I need to create a custom number format in Excel in the following format-
that, is the first three digits right of the decimal should be in one group and thereafter 2 digits in a group.
Tried to create it but cant understant how to...