In Excel VBA, you can call functions and subroutines within a macro using two main approaches:

1. Call Statement:

- This is the most common method.
- Use the `Call` statement followed by the name of the function or subroutine you want to execute.
- You can optionally include arguments within parentheses after the name.

Example:

```vba
Sub MacroExample()

' Call a function with no arguments
result = MyFunction

' Call a subroutine with arguments
Call MySubroutine(value1, value2)

End Sub

Function MyFunction() As Integer
' Function logic here
MyFunction = 10 ' Example return value
End Function

Sub MySubroutine(arg1 As Integer, arg2 As String)
' Subroutine logic here using arguments
Debug.Print "Argument 1:", arg1
Debug.Print "Argument 2:", arg2
End Sub
```

2. Direct Call:

- You can directly call a function or subroutine by simply using its name followed by parentheses (similar to how you call a built-in Excel function).
- Arguments, if any, are included within the parentheses.

Example:

```vba
Sub MacroExample()

' Call a function with no arguments
result = MyFunction()

' Call a subroutine with arguments
MySubroutine(value1, value2)

End Sub

Function MyFunction() As Integer
' Function logic here
MyFunction = 10 ' Example return value
End Function

Sub MySubroutine(arg1 As Integer, arg2 As String)
' Subroutine logic here using arguments
Debug.Print "Argument 1:", arg1
Debug.Print "Argument 2:", arg2
End Sub
```

Choosing the Method:

- Both methods achieve the same result.
- The `Call` statement is generally preferred for readability and explicitness.
- Direct calls can be more concise but might be less clear for complex logic.

Important points:

- Functions can return values, while subroutines don't (though they can modify variables within the macro).
- Ensure the function or subroutine you call is defined within the same VBA project or a referenced library.
- Properly handle any return values from functions for further use within your macro.

By understanding these methods, you can effectively call functions and subroutines to structure your VBA code for modularity and reusability, making your macros more organized and efficient.