Here's a great linen card from the New York World's Fair of 1939, showing the Marchant Calculating Company Display. According to the back of the card, the exhibit was located located in the Business Systems and Insurance Building, adjacent to the Trylon and Perisphere -- the "Theme Center" of the New York World's Fair.
Back then, calculators were mechanical, noisy, and expensive. I made the mistake of googling Marchant and came across tons of information on mechanical calculator history and "fan sites," spending a lot of time browsing as a result. Here's a model of a Marchant calculator around the same year as the Fair: