You have a couple of choices.

Either use the built in function $zhex or %SYSTEM.Utils.HexToDecimal or %SYSTEM.Utils.DecimalToHex.

See the documentation for details

Hope this helps.

Something like this should do it:

set x=""

set x = $o(@x)

while x'="" {

 write !,x," ",@x

 set x = $o(@x)

}