Michael, I copied and pasted the function into a new module as is., then
placed "=NotDigits(A1,B1)" into C6 after I entered
0 2 3 6 in A6 and 3 5 9 in B6 but only the "=NotDigits(A1,B1)" appeared
as my result in c6.
Well, you need to get you cell references right. My cell references
quoted your original post. If you put the the data of interest into
different cells, e.g. A6 and B6 as you write above, then you need to tell
that to NotDigits, as in "=NotDigits(A6,B6)".
Also the formula: SUBSTITUTE(SUBSTITUTE("0123456789",A5,""),B5,"")
it only display inself into c5 when I entered the following data
in A1= 0236 and B1=359
Conversely, if you put the data of interest into cells A1 and B1, you
need to invoke the second function as
"=SUBSTITUTE(SUBSTITUTE("0123456789",A1,""),B1,"").
You should also clarify what the actual numbers are you want to analyse;
why don't you show us the content of your cells A1, B1 (or A6, B6). As I
wrote before, which method you can use depends on the structure of you
numbers.