Search by regexp in Writer are wrong?

I have this text and search by regexp

[^\(](\d+\\\d+)

Why I found snippet like “(11\30)” ?
How to make regexp which match only digits without parenthesis?

Maybe (\d+).(\d+), why not?

how can it help to avoid digits after parenthesis?
No, it doesn’t solve the issue

In other words, do you want to find values in parentheses, but not highlight them? I was confused by Maria Ivanovna in your screenshot.

Use two consecutive searches - first find all values in brackets \(.+\) and then check the “Current selection only” and look for numbers with a separator

use [^(\d](\d+\\\d+) to not find 11\30 (since it starts with ( followed by a digit - hope that explains why) or use \s(\d+\\\d+)

Note: Why I found snippet like “(11\30)”? is an incorrect question. You find 11\30, which is a string surrounded by parenthesis.

Why I found snippet like “(11\30)” ?

No, you find not (11\30), but 11\30, because this found text matches your regexp [^\(](\d+\\\d+). Namely, the first character of the found text, 1, matches the [^\(]. The rest, 1\30, matches \d+\\\d+.

How to make regexp which match only digits without parenthesis?

E.g., (?<![(])\b\d+\\\d+\b, which uses a negative look-behind assertion (to not include that into the found text), and word boundaries. See ICU Regular Expressions documentation.

If you want to find only occurrences of a regex not immediately following an opening parenthese, you need to prefix it with a “negative lookbehind assertion”: (?<!\() as prefix should do. The related negative lookaghead assertion would be (?!\)). (The exclamation mark is a negated equal here, The < is used for “behind”.)
A “11\30” found in “( 11\30 )” (regard the spaces!) will still be a match, of course.
See Regex Tutorial - Lookahead and Lookbehind Zero-Length Assertions.

By the way: Whats your “11\30” meant to mean. Hopfully it’s not another fancy date format":

no, it’s just age of people by two different sources