My Dad's version was the supposed price of oil per barrel in dollars( bluffing) and the Arabs putting the price up from 142 to 154, then another 69. "And since then the price has gone up five-fold......"142 154 69 x 5
Cowboys and Indians.
You simply tapped the figures in, then turned the calculator around to show the result. Caused great amusement, and some people believed it! Of course, there were the clever ones who would say: "Hang on, you are not doing that right....."