ABSTRACT OF THE DISCLOSUREOne face of a tablet is divided into a plurality ofadjoining regions. The two edge regions at the right andleft have rows which in each region are divided into a pluralityof fields and are numbered continuously with primarily basicnumbers and their multiples, from one edge region continuinginto the next. A number of slides, equal to the number ofrows in each of the edge regions, lie loosely on the tablet,so that each slide may be pushed along the correspondingtwo rows which are at the same level of the edge regions inorder, as desired, to thereby at least partially cover oneor the other of these rows, so that the result of an arithme-tic operation carried out in one or the other region can beread from the exposed field adjacent the end of the correspond-ing slide.
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