I assumed they meant that a regex here could be used to just extract out the numbers and remove anything extraneous. They mention it fails with trailing charact

I assumed they meant that a regex here could be used to just extract out the numbers and remove anything extraneous. They mention it fails with trailing characters, or typical punctuation used in numbers (eg. dashes). A little regex to remove out anything non-digit would leave you with just the numbers to compare to the numbers in the list.