PowerPivot - Adding value from different column if blank

I am quite new to powerpivot and are trying to create a calculated column that displays the value from Column2 if a value exists, and the value from Column1 if blank - as shown in table below.

Have tried using IF/BLANK/ISBLANK and constantly getting a error. Is there some Dax functionalty that I need to understand, or how should I write the formula to make this happen?

Column1    Column2    CalculatedColumn
98765      983727     983727
82764                 82764
56824      922844     922844