Over at the Personal Finance & Money community, when I type 1040 into the search box in the upper right corner and hit Enter, it immediately returns the question with ID 1040, even though there are plenty of posts containing 1040. But when I type 193 into the search box, it returns a list of search results instead of the question with ID 193. Why the different behavior?
As explained here,if the search term is a number with at least four digits and this number is a valid ID of undeleted question, you will be redirected to that question regardless of search results.
So, this is by design and to actually look for such numbers, wrap them with quotes e.g. https://money.stackexchange.com/search?q=%221040%22