data verification
 

I have a large amount of data in a worksheet that was hand-entered. I want
to go back through and re-enter the data to double-check if there are any
mistakes. I know that there is a way to set up some sort of masking
worksheet that will compare a re-entered value to a previously entered value,
and if there is a content discrepancy, it will be highlighted of formatted in
some way.

For example, in Sheet 1, cell J9, I have the number "12269". So, if in the
alternate sheet I re-enter "12254", an error would pop up or something. Is
there a good way to do this? Thanks!