The u01b6 user exit converts a numeric expression to the number of units as defined by the TCL set-units, set-dozens, set-decimal, or set-thousands commands.
x = oconv(num.exp, "u01b6")
:set-dozens :u bp test 01 print oconv(24,"u01b6")
This program prints the value 2, as 24 = 2 dozen.