Tests are hard to solve for large number of users.
Checking the similar usage of such expression, I think there is something wrong with the sentence. What's the best and correct? a large number OR large numbers OR even something else!
English Language & Usage Stack Exchange is a question and answer site for linguists, etymologists, and serious English language enthusiasts. It only takes a minute to sign up.Sign up to join this community
These are both correct:
Tests are hard to solve for a large number of users.
Tests are hard to solve for large numbers of users.
The second sentence has a slightly more general connotation, like "users in general", whereas the first probably implies users of a specific application.
Thank you for your interest in this question.
Because it has attracted low-quality or spam answers that had to be removed, posting an answer now requires 10 reputation on this site (the association bonus does not count).
Would you like to answer one of these unanswered questions instead?