InfoPath Dev

I've have 1 field that required user to key-in 10 series number.

Then this value field need to 'auto' copy to another field inside the same form, but without 2 first digit. In other word this field will only store last 8 digit.

Below is the example:

Field1 : 1234567890

Field2 : 34567890

So my question, how can i remove the 2 first digit? did we have any formula can be use/set to this "Field2"?

Please assists, thanks advance.

Can u guide me in detail?

substring-before(double_click_to_insert_field,double_click_to_insert_field)

For my case:

substring-before(double_click_to_insert_field,Field1)

OR

substring-before(double_click_to_insert_field,Field2)

BTW what to put in here? (double_click_to_insert_field,Field1)

Finally i found the answer, thanks for the HINT!!

What i did is as below:

Set Rules Field1 - At CONDITION field1 begin with number (00) and set ACTION field2 with value substring(.,3)

Set Rules Field2 - At CONDITION field1 is blank and set ACTION field2 with value substring(field1,3)

So for those that have a same issue, please use above step. G.Luck!