I'll answer my own question.
It was staring me in the face!
= Table.AddColumn(#"Changed Type", "Inserted Power", each Number.Power(10,[#"Column_Name"]), type number)
Easy way to do is add column; custom calculation; raise to power 10.
= Table.AddColumn(#"Changed Type", "Inserted Power", each Number.Power([#"column_Name"], 10), type number)
Then swop 10 and Column_Name.
Peter
P.S. Sorry for wasting anyone's time.