Confusing Card Changes Its Spots

I was just a lad when I first saw this trick presented on television by a magician named Jules Cafari. It wasn't my introduction to Magic, but none-the-less I was intrigued. Since the trick was obtainable by a simple request in writing, (that was the accepted style of correspondence back then,) I quickly put pen to paper. All these years later, I decided to make one of my own to present in video form, and here it is. The magician shows a card with one spot on one side, and four spots on the other. This immediately turns into three spots, and six spots consecutively. The simple effect has of course been expanded to progress to eight spots, and this is performed with a large card suitable for stage presentation. I'll leave that for another day.