I asked my mother for the Panasonic 885 electronic calculator she used when I was a child. It uses four AA size batteries or an AC adaptor. Some of the keys no longer work, and I haven’t tried to check if the AC adaptor still works. The power switch reveals a red metal square when the unit is turned on. The case is made of imitation leather stitched at the edges and at the corners. I love its design—the colors, shapes, and fonts. I just found out that when holding the unit with the left hand (and pressing the keys using the right hand), the user could put his or her left thumb on the space with the word “Panasonic.”
The calculator allows you to repeat the previous operation multiple times by repeatedly pressing the equals key.
Shown above is the value -0.7734 with some non-zero value stored in memory. Shown below is the value 1234567890. Note the two “hyphens” on the upper left of the 7 and the 8; they indicate that the value has two more digits not shown on the right. With eight “hyphens,” one can calculate with 16-digit integers (but with reduced accuracy). Although the calculator can handle overflows (some numbers greater than 99999999 in magnitude), it cannot handle underflows (numbers less than 0.0000001 in magnitude).
My favorite way of playing with it when I was young was to repeatedly press the equals key until the number became too large or too small for the calculator to handle. Numbers that are too large result in an error message (seen below); numbers that are too small result in a zero.
Additional information about it can be found here.