Format changing in protected cell
 

How can i stop someone entering a %age into a protected cell? Is data
validation the only way?

The spreadsheet i thought was fool proof (shouldn't assume i guess!)
Someone has entered 5% into a cell that should read 5, and now all linked
cells are wrong, and 'the someone' can't change the format as i have
protected the sheet.

There is a master spreadsheet that everyone is using, so i could edit this
to hopefully stop this problem happening again!

Many thanks,