N Harkawat wrote:
=LEN(A1)-SUMPRODUCT(--ISNUMBER(-RIGHT(A1,ROW(INDIRECT("1:"&LEN(A1)))))

will tell you the number of text characters in the cell
....

Not reliably. If A1 contained JDR89765X, your formula returns 9 rather
than 4.

An alternative that works no matter how decimal numerals and other
characters are scrambled is

=SUMPRODUCT(LEN(SUBSTITUTE(G2,{0;1;2;3;4;5;6;7;8;9 },"")))-9*LEN(G2)