[header] How to block hotel rooms [title] Determine how many rooms you'll need. [step] Look over your guest or attendee list and count how many people will by travelling from out-of-town. Estimate that each of those persons will need a separate room. 
If you see a family on your list, try to guess how many rooms they'll need. It's even better if you can break down how many single-bed, double-bed, queen, king, or otherwise, rooms that you'll need.