I think what would be best here is to create a regex expression, reference .NET Regex Reference - Regex Storm.
UIPath has a great regex pattern builder that helps you, but its always good to reference some documentation. You may use “Matches” activity in studio and build a pattern. For example, if you know your account # always have 8 digits, you could use a pattern as the one below. You may also use the test text to test what the regex pattern is recognizing. This activity will then output all the matches it has found in a list.