function takes two arguments's length and width's and calculates the total area by multiplying them together

 
     Function Area(Length, Width)
         Area = Length * Width
     End Function
Sub aSub()
     MsgBox Area(100, 50)
End Sub

1.	Writing VBA Function Procedures
2.	A function returns a value to whomever called it. We can recast the previous sub into a function as follows:
3.	Call user-defined function in MsgBox
4.	Executing a Function Procedure from a Subroutine
5.	A function returns a value to whomever called it.
6.	One of simplest possible custom functions
7.	Convert Fahrenheit To Celsius
8.	Use ElseIf in a function
9.	Select Case in a function
10.	A function with one argument

function takes two arguments's length and width's and calculates the total area by multiplying them together : Function « Language Basics « VBA / Excel / Access / Word