The title block usually runs along the right edge or the bottom of the sheet. It also names the architect or engineer and holds the seal.
The sheet number tells you the discipline. A-201 is architectural. P-101 is plumbing. The revision block lists each reissue by number and date.
Check the date and the revision on every sheet you price. Check them against the sheet index. A wrong or old sheet gives a wrong takeoff.
Check the scale as well. If a sheet says not to scale, do not measure from it.