What is the easiest way to evaluate a 3x3 determinant?

Yes, Melody, that is the easiest.....we could also find it by the Method of Co-Factor Expansion, but that's more difficult.....!!!

I don't know about easiest but this is pretty easy.

https://www.khanacademy.org/math/precalculus/precalc-matrices/inverting_matrices/v/finding-the-determinant-of-a-3x3-matrix-method-1