ASP.NET Page Level Variable ?????

I am writing an application(asp.net webforms) whereby at the top of the page a claim number shows in an asp textbox. Under it there are about 14 tabs of information that all fall under the umbrella of the listed claim in the textbox. The user can ay of the following :

1) click a button to navigate to the previous claim,
2) click a button to go to the next claim
3) they can directly change (type) the number in the textbox, and hit enter.

Doing any of these actions will reload the information tabs (various calls back to the server happen) with new information related to the newly sought after claim. The user can go to a tab, type in new information, and hit a button on each tab to committ the new information.

Obviously in order for this to happen, I am referencing the claim number typed into the textbox quite often in my codebehind.  This is fine, but it actually starts to  become a performance issue because when I go to the database with the claim number I have to convert the text value of the textbox to an integer (ie. Convert.ToInt32(txtClaim.Text)...happens 96 times... becomes cumbersome) . <b>What I want is a way to simply reference the integer value set in the textbox</b> . I don't want to use a session variable or viewstate because with those variable types I would still have to do the conversion to integer.  EX (Convert.ToInt32(Session["claim"]).....this is no good). What I want is something like a page level integer variable that I can manipulate accross postbacks to keep the current value of the textbox handy. How to do ? Any information or advice would be greatly appreciated.