It provides an efficient method of displaying alphanumeric characters.
In some Soviet digital calculators of the 1970s, such as the Elektronika 4-71b, 9-segment displays were used to provide basic alphanumerics and avoid confusions with representing numbers in Soviet postcodes.
The extra two bars were slanted forward, allowing for an appropriate-looking И, and to differentiate the numeral 3 from the letter З.
The Sharp Compet calculator also uses a 9-segment display, allowing a small range of characters and symbols to be used.
[3] They are also used in some Epson Stylus printers, and Newport iSeries digital meters.