Style: SingleThe FX-991EX is s most advanced scientific calculator with 552 mathematical functions. Approved for Key Stages 3, 4 and 5, Recommended for advanced GCSE, a/as level and higher. Allowed in every UK exam where a calculator can be used. The large natural textbook display (Natural-V. P. A. M. ) shows mathematical expressions like roots and fractions as they appear in your textbooks which increases comprehension because results are easier to understand.