# Why is this considered a complete answer?

Recently, an answer of mine was deleted for being a complete answer to a question.

However, since I did not give the final value of the wavelength, why is this "a complete answer"?

You did give the final value. If the answer is $4$, and I write $2+2$ and leave it unevaluated, I gave the final value. An arithmetical computation is not a meaningful part of solving a problem, and if that is the only step that separates you from the answer, then the problem is done. Sorry but you don't have a case here -- the best you can do is to forget about this and move on.