I have a spreadsheet I'm creating in Excel to track jobs through the shop. In it I have some formulas to math for me. Problem is, it's really easy to accidentally delete or erase the formula and screw up the cell, so is there a way (without locking or requiring a password) to protect the formula inside that cell so it doesn't lose it's format and can still be typed in to? I know how to lock it, but then you can't add any new information, and the only other trick I know requires a password every time you want to add new information. Also, without the use of a 3rd party plug-in, is there a way to make a cell have a date finder calendar?