It was already her best subject back in the 1980s, when she attended William H. Carr Junior High School in Queens, New York.
"It just makes sense in my head," she explains. "I'm a very logical person and you can always prove your answers, and I liked that. You know right away if you're right or wrong. There's no grey area.
"I think I was on honor roll every semester. I was on the math team. I was a good student.
Chen says one of the things that made math her favorite subject was her favorite teacher: Eleanor Langberg, who taught 8th-grade algebra.
In The Early Show series, "My Favorite Teacher," Chen counts the ways this one stands out.
"She was also my homeroom teacher," Chen remembers. "So she was kind of more than just a math teacher to me. She was kind of like our mom at school. She was a nurturer, she was someone to respect and look up to and learn from.
"She was almost like a guidance counselor to us," Chen continued. "She really helped us shape our future."
It turns out Langberg remembered Chen as well.
"I saw her a number of years ago doing a weekend news show," Langberg says, "and I said to my husband, 'You know, George? I think that Julie Chen was in my class in junior high school. There's something in her face. I think I remember her.'
"And I took a chance. I wrote a letter to CBS at that point and said, 'If you are the Julie Chen who was in Junior HS 194, I want you to know I saw you on TV and I'm so proud of you. Please call me, contact me.' And she did.
"Sometimes I'm surprised to find her in the field of journalism," Langberg concedes. "I mean - I really was surprised to see that's where she ended up, because she could have had a nice career in mathematics, too."
Chen says Mrs. Langberg's real-life lessons are what she remembers most.
There was the time she had each member of the class pick a stock and follow it throughout the school year. "Eventually, we made graphs of it, and we stopped to see how much money we made at intervals.
"I think I was one of a few people that picked a stock that didn't turn a profit. It was Eastman Kodak. But, what are you going to do?
"Thankfully," Chen adds, "I've retained most of the equations I learned in class. But it's the foundation that Mrs. Langberg provided - not just in math, but in life, that led to my success."
And that success has left Langberg with a feeling of accomplishment as well.
"When you do accomplish something with certain children, there's a tremendous amount of satisfaction with that," Langberg concluded. "I'm proud to still be connected with her in a small way."