I like to make a custom field for my invoices in the structure of ogm like '+++090/9337/55493+++'

In order todo this 

- the first 10 numbers can be random (will be my client id and invoice number of the month)

- the last 2 numbers are the control number that you can get by dividing the first 10 numbers by the rest of the euclidean division by 97

- Before and after the numbers i have to add three +++ or ***

- In between i have to add a / after the first three and one after the first 6

How can i do this the formula field?