Why the number of ads found does not match the number in the search results on the pages?

Question

Parsing

When searching on real estate sites such as cyan, avito, yandex real estate, it writes that, for example, 50,000 ads were found, but in fact there are much fewer in the search results.
I can’t figure out where the rest are or does this counter show how many ads were in total?

Answer 1

Usually it shows how much is in the database, but then, for example, the 100th page does not let it go, that's all.