There are many ways an end user can run into this problem. One of the most common causes that I have seen is when pasting data. Enter the Datatype Sometimes when data is pasted, no matter if it is in a number format from the original source - it can be pasted as text or in string format. Strings are great, they can help display data in a wide variety ways, including numbers … [Read more...] about Why Don’t My Columns Add in Excel?