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Donald Trump was a frequent and favorite guest on Howard Stern’s radio show, and one day in 2006 he brought his children Ivanka and Donald Jr., along for an episode. At one point during the nearly hour-long appearance, the Trump kids explained how they got into the famed Wharton School at the University of Pennsylvania, their dad’s alma mater, on their own merits. The pair talked up their high SAT scores and told Stern that no one, even parents of friends who allegedly donated large amounts to Wharton, could buy their way into the school.

Then Stern gave the Trumps a pop quiz in simple math. The kids struggled to get the answer right—and Trump himself couldn’t do the basic calculation. But, in what might have been a telling moment, the elder Trump insisted that his answer was correct.