I have four fields that I'm adding together.  The fields being totalled all have a data type of currency.  When added together, although the number returned is correct, it's a plain text field which I'm unable to change.  How do I change this to return either a number or currency type?

(ifnull(emcr."Live £", 0) + ifnull(emcr."Locked In £", 0) + ifnull(gmcr."Live £", 0) + ifnull(gmcr."Locked In £", 0)) as 'Live/Locked In Revenue'