Gary''s Student wrote...
Sub findmax()

If there were OBVIOUSLY something for which a FUNCTION would be most
appropriate, this is it!

Dim r As Range
Set r = Selection
v = r.Cells(1, 1).Value
For Each r In Selection
If r.Value v Then
v = r.Value
s = r.Address
End If
Next
MsgBox ("maximum value " & v & " found in cell " & s)
End Sub

This can easily be converted into a function as well.

Should NEVER have been offerred as a sub. Parametrizing the function
isn't completely trivial, and deciding what to return (range object
pointing to the cell containing the max value, a string containing the
cell's address or an array of row and column indices) is worthy of some
thought.

Also inefficient. No reason to search through the entire range.
WorksheetFunction.Max will return the max value more quickly than
iterating through the range in VBA, then exit when the first instance
of the max value is found. The following returns the address of that
cell.

Function foo(rng As Range) As String
Dim c As Range, x As Double
x = Application.WorksheetFunction.Max(rng)
For Each c In rng
If c = x Then
foo = c.Address(0, 0)
Exit Function
End If
Next c
End Function

There's also the question of which direction to search. That is, if the
range contained

1 1 1 9 1
2 1 3 1 1
3 1 2 2 3
9 3 1 1 2
2 1 1 3 2

should the 9 in the top row or the 9 in the leftmost column be
considered the first max value found?

Finally, no need for udfs. This can be done with an array formula. If
the range were named D,

=ADDRESS(INT(MIN(IF(D=MAX(D),ROW(D)*1000+COLUMN(D) ))/1000),
MOD(MIN(IF(D=MAX(D),ROW(D)*1000+COLUMN(D))),1000))

would return the address of topmost then leftmost max value and

=ADDRESS(MOD(MIN(IF(D=MAX(D),ROW(D)+1000*COLUMN(D) )),1000),
INT(MIN(IF(D=MAX(D),ROW(D)+1000*COLUMN(D)))/1000))

would return the address of the leftmost then topmost max value.