If you don’t have to do these kinds of rough calculations many times a day I don’t see this as a worthwhile skill (you could simply ask Siri/WolframAlpha, for example), other than perhaps to consolidate one’s authority (if you really have to play that game).
If you don’t have to do these kinds of rough calculations many times a day I don’t see this as a worthwhile skill (you could simply ask Siri/WolframAlpha, for example), other than perhaps to consolidate one’s authority (if you really have to play that game).