Casio fx-83 is the UK's best-selling Scientific calculator for Secondary School education Fx-83gtx is the new upgraded version of the fx-83gtplus Allowed in every UK exam where a calculator can be used Recommended and approved for use within key stages 3 and 4, to include GCSE, National and higher, Junior and leaving. Natural textbook display natural-v.P.A.M., shows Mathematical expressions as they appear in textbooks