How use the DAYS360() function for "30E/360" Day Count Convention calculation?

If you are using the Microsoft Excel software to calculate Accrued Interest based on the 30E/360 Day Count Convention, you can use the DASY360() to count days in an Accrual Region:

DAYS360(start_date,end_date,[method])

Start_date, end_date    
  Required. The two dates between which you want
  to know the number of days. If start_date occurs after 
  end_date, the DAYS360 function returns a negative number. 
  Dates should be entered by using the DATE function, 
  or derived from the results of other formulas or functions. 

Method    
  Optional. A logical value that specifies whether to use 
  the U.S. or European method in the calculation.
  
  TRUE: U.S. (NASD) method. If the starting date is the 
  last day of a month, it becomes equal to the 30th day 
  of the same month. If the ending date is the last day 
  of a month and the starting date is earlier than the 30th 
  day of a month, the ending date becomes equal to the 1st 
  day of the next month; otherwise the ending date becomes 
  equal to the 30th day of the same month.

  FALSE: European method. Starting dates and ending dates 
  that occur on the 31st day of a month become equal to the 
  30th day of the same month. 

So we can use DASY360(T1,T2,FALSE) to count days in an Accrual Region for the 30E/360 convention:

[T1,T2) = The Accrual Region 
DiR(T1,T2) = DAYS360(T1,T2,TRUE) 
DiY(T1,T2) = 360 

Day_Count_Factor(T1,T2) 
  = DiR(T1,T2) / DiY(T1,T2)
  = DAYS360(T1,T2,TRUE) / 360 

Accrued_Interest(T1,T2) 
  = Principal × Interest_Rate × Day_Count_Factor(T1,T2) 
  = Principal × Interest_Rate × DAYS360(T1,T2,TRUE) / 360 

Note that other spreadsheet software (LibreOffice, OpenOffice) also offer the same DAYS360() function.

References:

• DAYS360 function, microsoft.com.

⇒ "30E/360" - Whole Accrual Period

⇐ "30E/360" - Day Count Examples by ISDA

⇑ Day Count Convention - "30E/360"

⇑⇑ Day Count Conventions