Odoo 15 and prior had an Ndays magic variable that could be used to insert the number of days in a period into a custom accounting report formula, looking at the Odoo16 documentation I can't find any similar functionality. 

Is there a way to handle this? 

I have a specific and probably unusual need to compute a payroll adjustment for contractual purposes so I need to subtract actual payroll total from a nominal payroll number. The nominal payroll number is just nominal_annual_payroll*(Ndays/365), but I can't figure out how to get the Ndays equivilet in Odoo 16.