In the financial calculations, the DAYS360 function returns number of total days between two dates based on a 360 day year count.
DAYS360(start_date, end_date, [method])
start_date – Required. The start date to use in the calculation.
end_date – Required. The end date to use in the calculation.
[method] – Optional. An indicator to describe what day count method to use. Available options are US method and European method. The default value is Zero.
Why don’t we use 365 day year?
We use the 360 day year for interest calculations. Below is given an example demonstrating deference between both year count.
For more detail, visit Google official website.