FIELD: educational aids manufacturing. SUBSTANCE: device has matrix cells data carrier made from paper cards, case with groove, movable stencil with rectangular windows for matrix cells content recording and visualizing, cap with identical windows and movable lathes. Stencil windows can be overlapping by plugs but plugs windows can be overlapping by movable lathes. Stencil and cap has guiding slots for plugs and lathes moving along. Plugs of windows of fourth vertical column at left hand have marks, but corresponding caps have marks. EFFECT: better visual training aids for matrix determinant counting, more promoting selection of correct product of matrix elements owing to mnemonic rule using. 2 cl, 13 dwg
