How to Remove first letter from the Field value

Hallo Every one,

Could you please let me know how to split or remove the First Letter or Alphanumeric Character from the value of a filed.

For instance Let us say:

A123456,here I need to remove the A letter and want to dispaly the above mentioned with out 'A'. as 123456 alone. on the input as A123456 as some Input.

Please help me.

Regards.