Unitrex mini 8 LED Handheld Calculator

The Unitrex mini 8 calculator has a 8 digit LED display. The display is actually very tiny and need a magnifying plastic bubble over each digit to make them legible. The determination to use what is available to make a calculator smaller is amazing.  Other displays then were either large or consume too much battery power.

Closeup of the LED digits, nice and bright even at a battery voltage of 8V ( down from a fresh battery of 9V )

The need to make the calculator small  means that a small  9V battery has to be used. A drawback is the limited energy capacity in alkaline( back then it is manganese battery ) 9V batteries.

This calculator even comes with a DC input adapter socket, for use at the desk, batteries could be expensive back in 1975 when the calculator was first introduced by Eiko Business Machinese Co Ltd of Japan.

I have no idea why they put a carrying strap on the calculator. But this strap here probably has acquired some ink stains from some office worker.