Thanks Colin,
It works




I'm going to use this rule for a range of cell $A$2:$E$10, where $A$1:$E$3 is a header row.
I assigned the formula =OR(ISNUMBER(FIND(Letters,A1))) to the range - and it's working. I don't understand that. FIND(find text1, within text2) - the function returns position number of text2 in text1. My A1 contains some text without T, F, A, and when I enter a, f, or t in $A$2:$E$10 I'm getting formated text.

Attached Files

Book1-ConditionalFormating.xlsx (9.8 KB, 13 views)