Convert decimal to big int in .addDay() function

Convert decimal to big int in .addDay() function

I am trying to use the .addDay() function but the number of days will be determined by a calculation using several date fields.  

I'm getting the following error and don't know how to avoid it.

Mismatch data type for function addDay at argument index 1 expected data type BIGINT found dataType DECIMAL

The code I'm using is as follows:
  1. request.Date = request.Date.addDay(((request.End_Date - request.Start_Date) /  (1000  *  60  *  60  *  24)));

I know there is a function to change a big to decimal but is there one to convert a decimal to a bigint?


Date, End_Date, and Start_Date are all date fields.  

I think that the following code is returning a decimal, how can i make this return a bigint?
((request.End_Date - request.Start_Date) /  (1000  *  60  *  60  *  24)  )



Thanks