4. The invention as defined in claim 3 including: detent means intercoupled between said decoder and said movable means for releasably holding said movable means in a selected position.
4. The invention as defined in claim 3 including: detent means intercoupled between said decoder and said movable means for releasably holding said movable means in a selected position. 5. The invention as defined in claim 4 wherein: said movable means is a rotary mounted wheel having a set of answer symbols carried on the edge marginal region thereof in alignment with said openings for selective display of a given symbol in said set.