Faster Than a Calculator, Professor Gets the Answer and Hooks Youths on Math

He talks like a performer, acts like a magician and multiplies faster than a calculator.

Arthur T. Benjamin is a math whiz, and his life goal is to make people excited about mathematics.

On a recent morning in Claremont, he did just that.

About 100 Pomona Valley high school students watched in amazement as Benjamin, a professor of mathematics at Harvey Mudd College, used his formulas to prove that, with practice, anyone can square and multiply four-digit numbers in seconds.

“Everything that I’m doing is perfectly natural. There are no tricks,” he told audience members as he raced with them to be the first to answer problems that multiplied one four-digit number by another. The competition was not really fair: the audience had calculators and Benjamin didn’t.

But with each problem, Benjamin, 28, produced the answers faster than the calculators.

The first step Benjamin used in this method was memorizing multiplications by the tens, hundreds and thousands. Breaking with the traditional method, he said he had to learn to add numbers from left to right. “It’s a habit that takes a while to break,” he said. But, it’s faster.

He showed his audience shortcuts to squaring a large number by simply moving it several digits forward and backward and then doing some simple multiplication.

Taking his audience a step further, he also showed them how to remember large numbers when working out problems mentally. He demonstrated this by turning his back to the board while a student called out a 16-digit number. Another student wrote the number on the board for the audience to see. After about 30 seconds, Benjamin repeated the number by memory as the students watched in awe.

Benjamin explained that he was able to remember the number by using a phonetic code he learned in a memory book. “For every digit, I have a consonant sound associated with it. Once you got the code memorized, you can create words instead of numbers,” he said.

His 45-minute presentation ended with a grand finale of squaring a five-digit number in about 30 seconds.

In the midst of applause, Pomona High School sophomore Arnold Lopez, 16, said: “I thought it was excellent. I would like to do this someday. It was amazing.”

Lopez is interested in science and is a member of the college sponsored Mathematics, Engineering, Science Achievement (MESA) program, as were the other students at Benjamin’s presentation. The program, created to increase the number of minorities who graduate with four-year mathematics degrees, operates on college and university campuses throughout California.

Benjamin, who has been doing his shows for about 10 years, said he loves working with students.

“I’m trying to provide a spark for students in mathematics,” he said. “The way (math) is taught in school is very mechanical. The way I do it, it’s fun and done in a creative way.”

Pomona High School senior James Hernandez, 17, said he was entertained by the presentation. “It was pretty good. He was really quick,” he said. “His memorization . . . I couldn’t see how he did it.”

Hernandez, who is college-bound, wants to major in engineering.

Pomona senior Ottoniel Doerng, 17, who wants to be a nuclear engineer, said he plans on practicing this method in the future.

“It was very amazing,” Doerng said. “Teachers from high schools should use that method because you can multiply with large numbers. It looks easier from the left to right.”

Damien High School senior Tom Arambula is also applying to colleges and wants to be an electrical engineer.

“It was just amazing how quick he can do all that,” he said. “It’s an easy trick to learn. It’s a faster way at getting the multiplications down. I’m going to use this method now when I take tests.

Before concluding, Benjamin gave two pieces of advice to his audience. First, he encouraged students who are interested in math and sciences to apply to Harvey Mudd College. Then, he urged them to major in the math and science fields even if their interests were in other areas.

“Math is best because people who know math, know how to think,” he said. “That’s what they want out there. Employers want to make sure that people know how to think logically, critically and independently, and mathematics forces you to think that way.”

Benjamin said he had always been interested in patterns and puzzles for as long as he could remember. He always wanted to discover how things worked, he said.

As a child, Benjamin was also interested in magic. He performed magic shows and would include his math tricks. “People responded so well to them that it gave me the incentive to improve my calculation skills and to become more proficient,” he said.

“Whether you’re doing a magic show or a class, you have to get the students’ participation. It’s important to interact with students,” he said. “The connection between magic and math is you have the problem-solving element.”

Benjamin said he still uses card tricks to get his point across in the classroom.

“This is my very first full-time teaching position,” he said. “I’m a ham, and I love performing and sharing my ideas and teaching with the right combination of both.”

He came to Harvey Mudd this fall after graduating from Johns Hopkins University in Baltimore, Md. He received his bachelor of science degree in 1983 from Carnegie Mellon University in applied mathematics and received both his master of science education degree and his Ph.D. from Johns Hopkins University in mathematical sciences.

Through presentations similar to this, Benjamin said he hopes to increase the number of students majoring in math and sciences, especially women and minorities.

“I hope to spread the word of mathematics to everyone,” he said. “It is important to get these students especially interested in the mathematical sciences and engineering. This is the future of our work force.”