DATEVALUE() function?

[john w]

I need to convert a Date in InDe to a serialized number like in Excel or Google Sheets. I am looking for something like this "The DATEVALUE function is used in Excel and Google Sheets to convert a date represented as text into a serial number that can be used in date calculations. This serial number represents the number of days that have passed since January 1, 1900."

How do I achieve something like this in Instant Developer. I need to use the date numbers in a Slope calc.

Any help is appreciated.