The famous real estate developer Gerald D Hines used a slide rule constantly - it gave him time to think of answers to questions while clients watched him go th

The famous real estate developer Gerald D Hines used a slide rule constantly - it gave him time to think of answers to questions while clients watched him go through the motions of some calculation. It also helped him quickly do actual sums to scope out the major dimensions and costs of a project, further impressing clients. This was before pocket calculators, of course, but slide rules were probably more mesmerising to watch in action anyway.