MathTalks Lecture: "Breaking Driver's License Codes"

April 23, 2012

MathTalks speaker Joseph Gallian

By Laura Pochodylo ‘14

More than 20 years ago, Joseph Gallian deciphered the way that three states assigned driver's license numbers. It was simply "something I had fun with," he told a Knox College audience.

Gallian, Morse Alumni Distinguished University Professor of Teaching at the University of Minnesota-Duluth, delivered a lecture at Knox, "Breaking Driver's License Codes." The April 4 event was part of the MathTalks lecture series sponsored by Dale Nelson, a 1958 Knox graduate, actuary, and national authority in the field of automobile insurance.

Gallian's work has been valuable in a practical sense. For example, he was contacted by a cancer researcher who needed the Minnesota license number formula to obtain the current addresses of patients from a database that could be queried only by license numbers.

"You can never tell when something might be useful, but I just did it for fun," Gallian said.

Knox College Assistant Professor of Mathematics Pedro Teixeira said the lecture was interesting and accessible.

"It's a challenge to present technical material to a general audience," Teixeira said. "Professor Gallian investigated an interesting problem using elementary mathematical tools, critical thinking, and methods similar to those used in the experimental sciences, and he was able to present his methods and results in a very accessible way."

Gallian explained the origins of his research into assigning driver's license numbers, saying that at first he had been interested in grocery store bar codes.

He theorized the long numbers on each license included information about the driver's full name and birthday.

"I just used the guess-and-test method," Gallian said. "And there was no Internet in those days."

Gallian published his findings in Mathematics Magazine. After uncovering the formula for assigning driver's license numbers in Minnesota, he decided to find out what he could about the systems in other states.

"I found out most states have a random system," Gallian said.

His work captured media attention, and the St. Louis Post-Dispatch published an article about Gallian and his successful effort to crack Missouri's secret code of assigning driver's license numbers.

"Missouri has an incredibly complicated scheme," Gallian said.

Gallian pointed out that his examination of driver's license numbers took place years ago. Since then, he said, there has been a "massive change" in the way states generate driver's license numbers.

While at Knox, Gallian also delivered a second presentation, "Using Mathematics to Create Symmetry Patterns," on April 5.

Teixeira said he feels the two lectures were linked by a relevant lesson for both math students and the general audience.

"One interesting message (Gallian) conveyed was how something done just for intellectual curiosity or just for fun can lead to unexpected applications," Teixeira said.