So, I can do it mentally, but it does technically take more effort and brain work than using the calculator. In this example it's obvious that we should be able to reason out the answer, but I would hardly say calculators are ever the problem. Ultimately they are a tool, and for most people knowing how to use a tool is good enough.
I always think of calculating triangles with sin cos tan, and the fact that we were taught how to use the calculator and only the calculator. I assume there is a long handed version you can do with pen and paper, and I assume you eventually know it if you study mathmatics, but for most people knowing how to use the calculator is probably sufficient.
And as we've learned now, they probably don't even know that.