pocket vintage calculator with solar power

80s 90s accounting addition antique background banking bankrupt battery both business button calculate calculation calculator classic college colourful digital display divide division economy education eight electronic figures finance five four isolated keyboard keypad lcd limited math mathematical maths memory minus money multiplication multiply nine nostalgia numbers obsolete office old oldfashioned one operations past pastel percentage plastic pocket power punchy retro root school seven six solar square subtract subtraction tax technology three traditional two university vibrant vintage wealth zero