Take a look at

http://cpearson.com/excel/duplicat.htm

In article ,
"Gary" wrote:

Each day I work with two worksheets. One is a list of numbers that is given
to me by someone else. The other list is something I make myself, again it is
a list of numbers. I need to know if there is a way I can compare the data to
find out if any of the numbers I input on my list match up to the ones on the
list I am given. I am aware of the "Find" function, but I'm working with
lists of hundreds of numbers, and it's really annoying to take each one and
"find" it on another worksheet. Any answers?