They’re only 9 and 11 years old, two Bethesda brothers already are winning big. They're getting paid trips to London and California, plus thousands of dollars worth in scholarships.

The best part-- they’re doing so because of Pokémon.

This doesn't have to do with Pokémon Go, the smartphone game that consumed everyone last year. Liam and Walker Halliburton are schooling us in the actual Pokémon card game: a game of probability, strategy and numbers.

"So, you have to be good at math to do this. So, I can't play this game,” said WUSA9 reporter Stephanie Ramirez. She didn’t get any laughs. Just a straight forward, "If you're good at math you can,” from Walker Halliburton.

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They’re pretty serious about it. Liam's parents said he took home a $10,000 dollar scholarship and won the National Championships last year. The Bethesda brothers recently scored in the Top 8 in an even bigger tournament this year, which means a paid trip to California for the championships next month.

Their parents say these competitions have become their vacations.

"I like the game because it’s fun and you can meet friends that you can play with,” said Walker. His brother Liam said he also likes the people they get to meet.

Their father said it started about three years ago when Liam's school friends were trading cards. So, he wanted a pack.

"I'm not going to just buy you a bunch of cards so you can give them to all your friends. That sounds insane,” said Halliburton, who did eventually purchase the cards. He also took Liam to a local game shop so he could learn the game.

Fast forward a few years and their son won a paid trip to London to compete.

"I think early on, we talked about how it was teaching our kids good sportsmanship,” said Liam and Walker’s mom, Connie Hwang. She said there the game comes with a lot of losing as well.

Dad said he enjoys the take-down strategy.

"I always tell people one of my proudest moments was at the World Championship two years ago. Liam came over and he said to me, you know, 'Awe, I lost that last round,' and I said, 'What happened Liam?' And he said, 'Well, I had nine cards left in deck and I knew there were two cards and if I drew either one of them I would win. So I made these plays to allow me to draw seven cards and I didn't get it. So I lost. And I said, 'I love you son.' If that's not doing the right thing I don't know what is! ”Halliburton said.

"Kind of like poker, just calling it. Calling what your opponent is going to do,” said Liam.