I've definitely owned a Casio calculator that worked on fractions rather than decimals and could even work in terms of roots and certain irrational numbers like

I've definitely owned a Casio calculator that worked on fractions rather than decimals and could even work in terms of roots and certain irrational numbers like e and pi. For example, sqrt(2) + sqrt(8) would print 3 sqrt(2) rather than 4.242640687119286~ I wish I knew how it worked, it's probably something simple like suggested in another comment.