using contains for multiple numbers

[Richard D. Williams]

I have not done this, for a long time and I know I have see it done.

I have a field that may or may not contain a number (0-9).

I want to write an IF statement testing this to be true or false.

Is it,
if  : 4 co "123467890"

or

if  : "1234567890" co 4

or
if  : "0|1|2|3|4|5|6|7|8|9" co 4

I just can't remember that correct syntax.

I am probably way off with my guesses.

Any help?

Richard D. Williams