NEW YORK — A Florida man who trained for a national memory competition by memorizing a randomly shuffled deck of cards as he climbed Mount Everest won the mental bout Saturday and broke a U.S. record.

Nelson Dellis, 28, of Miami, said his rigorous training for the challenge required him to reshuffle the deck of cards at each new altitude in his climb.

“I was getting my best times the higher I got,” said Dellis, who was surprised at his ability to stay focused as he made his way toward the summit before having to stop because of problems with his oxygen mask. “I was getting so much, much less oxygen up there.”

It was the second year in a row that Dellis won the USA Memory Championship, which was held in Manhattan. He also broke a record for memorizing 303 random numbers in five minutes, besting the previous record of 248 numbers in five minutes, which he himself set last year.

“It’s all tricks,” Dellis explained of his win. “I don’t have a good memory naturally. It’s something I learned and taught myself.”

Among the tricks he relies on is an ancient method he refers to as the “journey method,” where he visualizes memorized objects as he moves mentally through a place he knows well. To recall the information, he mentally walks back through the journey. About 50 people competed in Saturday’s challenge of mnemonic skills that required them to recall random information including 99 names and faces, a 50-line unpublished poem and 200 random words.

Texan Ron White, the 2010 national memory champion, came in second; Michael Mirski, a 19-year-old sophomore at the University of Pennsylvania, came in third.

Four-time winners Hershey High School in Hershey, Pa., won its fifth title in a competition against groups from another high school and the University of Pennsylvania.

The competition, now in its 15th year, was founded by a former IBM executive to promote the capabilities of the human brain.

Dellis, a former software developer turned “memory consultant,” said he was compelled to research the mysteries of memory after his paternal grandmother began showing symptoms of Alzheimer’s disease and died in 2009.

He said he always thought memory was static, but he learned he was wrong: “The mind is trainable.”