Manual calculator for analog and digital numbers

A manual calculator useful in registering numbers and in converting whole and fractional numbers from one numbering system to another numbering system and comprising back cover means:

• front cover means having a configuration matching that of said back cover means and being secured thereto in a congruent position;
• and a plurality of elongate slide members arranged in a parallel array between said cover means and each being movable longitudinally relative to said from cover means between first and second positions;
• said slide members each bearing indicia indicative of a first state associated with said first position and a second state associated with said second position;
• said front cover means defining an elongate window in which the indicia borne by the slide members are visible in a parallel array indicative of a selected number series in a first numbering system;
• and said front cover means bearing a plurality of sets of indicia with each set having a predetermined correlation to number series expressed in a preselected one of numbering systems including decimal, octal, hexadecimal, and binary coded decimal;
• said sets of indicia being arranged relative to said window and said slide member with each set in a corresponding row parallel to said window and said plurality of stes in columns perpendicular to the direction of movement of said slide members and with numerical values in each said system aligned with a corresponding one of said slide members whereby the positions of said slide members may be manipulated to indicate corresponding number series in different numbering systems.