Kingson FourRule 


Kingson FourRule Calculator Is a SlideRule on one side and a 6decade "Addiator" type calculator on the other side. For use with totals up to 999,999, or, by putting the decimal point two places from the right, currenccies up to 9,999.99 Addition and subtraction using the "Addiator" type calculator (see the Addiator in this section) and multiplication, division, square roots, and reciprocals using the slide rule. 160 x 40 x 8 mm (6.25" x 1.6" x 0.3"). 1960s to early 1970s. Made in Hong Kong.
This was a way of incorporating the full four functions, as well as square roots and reciprocals, into a pocketsized calculator which was much, much cheaper than the early electronic calculators. 


Vintage Calculators 

© Text & photographs copyright Nigel Tout 20002015 except where noted otherwise. 