In Google spreadsheets, I need a formula to extract all digits (0 to 9) contained into an arbitrary string, that might contain any possible character and put them into a single
You may replace all non-digit characters using the \D+ regex and an empty string replacement with
\D+
=REGEXREPLACE(A11,"\D+", "")
or with casting it to a number:
=VALUE(REGEXREPLACE(A11,"\D+", ""))