U2 drummer Larry Mullen Jr. has revealed a learning disability that causes him to struggle with counting.

“I’ve always known that there’s something not particularly right with the way that I deal with numbers. I’m numerically challenged,” the rocker explained during a conversation with The Times. “And I realized recently that I have dyscalculia, which is a sub-version of dyslexia. So I can’t count [and] I can’t add.”

Dyscalculia is a learning disability that impacts a person’s capacity to comprehend all things number-related, including math, telling time and – most notably in Mullen’s case – reading music. As a result, the drummer often struggles while performing.

“When people watch me play sometimes, they say, ‘you look pained’. I am pained because I’m trying to count the bars,” Mullen said. “I had to find ways of doing this — and counting bars is like climbing Everest.”

READ MORE: 10 Best U2 Songs

Mullen was only recently diagnosed with dyscalculia, but he has been struggling with the issue for most of his life. In addition to music, he noted the “counting challenges” impacted his education as a child.

Mullen further addresses his struggle with dyscalculia in a new documentary called Left Behind. The film chronicles five mothers’ efforts to establish the first state school in New York City for children with dyslexia.

According to studies, dyscalculia affects roughly 5-8% of the U.S. population.

Is U2 Working on New Music?

Mullen wasn’t able to participate in U2’s celebrated 2023 residency at the Sphere as he recovered from surgery, but he’s back with the Irish band now as they prep their next album alongside producer Brian Eno.

“We’ve got [Mullen] in the studio,” guitarist the Edge reported during a recent conversation with BBC Radio 2. “He’s good. He’s taking it easy, but he’s back in the saddle on the drums [and] doing some recording with us. And so we’ll be doing a bit more of that before the end of the year.”