title: Compare data of two Excel Columns A & B, and show data of Column A that do not exist in B
body: <p>I have an Excel file that has columns A and B, both have data that may or may not exist in other column, I'm only interested in the data of column A that do not exist in B. These Columns have same Header names. What formula can I use to show which items in column A aren't in B?</p>