User asked a question on Quora that, How and Why Google is showing p*rn results in when one type equation -4(1/4) into Google search query? This is really a very strange bug on Google. The bug was apparently uncovered via when user tried to use Google for solving mathematical equations, but the search engine misinterpret his queries. Google said, A team of highly trained monkeys has been dispatched to deal with this situation. We are working on a bug fix.
Source: https://thehackernews.com/2013/02/google-seach-engine-flaw-impossible.html