Calculadora nueva, estuche usado. Ver fotos.The APF 3550 is an arithmetic calculator with 8 digits precision and algebraic logic. It has 6 functions, 24 keys, and an LCD (liquid crystal) display. Facts at a glance: Feature Value Type: Arithmetic Functions: 6 Keys: 24 Precision: 8 Logic: Algebraic Display type: LCD Year introduced: 1985