The Casio fx-991ES is a scientific calculator with 8 digits precision and formula input logic. It has 403 functions, 50 keys, and an LCD (liquid crystal) display. The power source is Solar. The calculator was manufactured in China. Note: Functionally the same as fx-570ES with solar power
This model replaces the deleted FX991ES. New features of the FX991ES PLUS are a new equation mode and addition of random integers.