Simplify the following text for a Grade 6 native English-speaking person.
Original: Lars Petrus ( born in 1960 ) made his name as an internationally accomplished speedcuber in 1982 when he became the national champion of Sweden , and went on to finish fourth overall at the first official Rubik 's Cube World Championships held in Budapest , Hungary . He later published his unique method , known as the Petrus system , on the Internet .
Simplified: Lars Petrus is the creator of the petrus method for the Rubik 's Cube .