Problem using custom forms

Hi, I recently decided to edit the QuickPress custom form to make it match what i want. So the problem is I declared a variable and then used the post function to get the data from the form into the post and came towards this problem.

Its hard to explain but heres what happened.

Variable id_number declared.
PHP gets the value user inputs in form and stores it in that variable.
Variable is then published.
But When i go to edit post inside wordpress admin, inside the post i get the variable $id_number rather than the actual number the user inputted but it works fine when its published, its just that the variable shows instead of the integer when editing.

How do I fix this that the variable shows as the integer rather than its variable name?