I currently have this formula:

=IF(_CUST.TYPE="N",'Att. - 2014'!CJ10*13.8,IF(_CUST.TYPE="C",'Att. - 2014'!CJ10*10.8,IF(_CUST.TYPE="U",'Att. - 2014'!CJ10*13.8,IF(_CUST.TYPE="CU",'Att. - 2014'!CJ10*10.8,IF(ISBLANK(_CUST.TYPE)," ")))))

Basically:

If the Cust. Type is "N" or "U" then I want it to multiply [selected cell] by £13.80
If the Cust. Type is "C" or "CU" then I want it to multiply [selected cell] by £10.80

Is there a way I can simplify the above formula? Am I able to use the "OR" function? If so, how do I do it?

Thanks!