Cause I’m Mr Brightside shirt

This includes simple arithmetic and probability calculations. Usually the calculations are necessary to analyze the data to get something meaningful out of them (calculating Net Present Value of a project, making financial models, determining which products are selling which are not, analyzing customer buying behavior etc.) I do a lot of calculations; sometimes mentally (like the one above and other smaller ones), otherwise (the bulk of it) on excel. During interviews I had to solve some difficult problems without excel, but again not on the job. None of the calculations went beyond the basics though.