Counting number of days in a month

Hey guys,

I'm trying to calculate the total number of days in a month. I used the Approximate Count Distinct Function but the counts are inaccurate (April has 29 days even though all the dates recorded a lot of data).

The end goal is to calculate Average Daily Hours Spent at a Monthly level. I'm hoping that once I can count the number of days in a month, I can use the below formula.

Pull by Month

=(Total Seconds Spent/3600)/Days in a month

Any help is appreciated as I'm new to this. Thank you very much.