Abstract: A waterproof advertising display device includes a captive calculator and is particularly adapted for use on a shopping cart of the telescopingly nestable type. Broadly speaking, the display device includes a display plate for mounting on the front wall of a shopping cart upper rear receptacle and for receiving advertising copy and a transparent cover plate attached with keyed quick release fastener and forward release hinge over the advertising copy to the display plate. A tongue and groove seal between the plates keeps water from the advertising copy. A calculator assembly is attached to the upper right of the cover plate and includes a slanted blind channel shelf for holding a captive calculator at a preferred angle for use by a shopper. A plug/bumper attached after insertion of the calculator prevents calculator removal and protects the calculator from impact upon nesting of shopping carts.