here is a rather splendid ten digit scientific from 1975.
it has the early casio *baroque* style of the period, shared by the
older fx-10 and the briefcase models 103-mr
& 803-mr with a square-jaw case and square
edged buttons.
the function set is similar but less complete than the later fx-19,
but this model has 10 digits. it also takes 4AA cells. the display is very
good with a spare digit for minus and the gap between a ten digit mantissa
and the two digit exponent.

conceptually this is a throwback to the fx-10,
but the function set is much improved and the calculation speed increased.
the right most digit flickers whilst calculating like the fx-20
and the small zero digit has gone and exponents of up to +/-99 are
allowed.

a switch for degrees or radians has appeared, but no sign yet of
gradians or fractions. like earlier models a * 10^x* button is not
present, since * x^y* can be used for this, although conveniently this model
has a * x^2* button which doesnt appear again until *arc* is replaced by
an *inv* button on later models like the fx-39.