I ranked first in my university in my undergrads, which had many affiliated colleges. How can I specify that in an essay in a compelling yet precise manner?
From your comments, it is perfectly fine to state that you ranked 1 in the university. In my case I had been asked to provide the number of students. I had no difficulty since mine was a National institute which is a university by itself, all I had to do is to count the number of students in my class. But in your case you might have to give a brief explanation about the affiliation, possibly an attestation from the University and college.