Complex sentence: Thomas Clausen (born January 16,1801; died May 23,1885) was a Danish mathematician and astronomer, best known for his discovery of a factor of the sixth Fermat number (1854).
Split into simpler sentences: Thomas Clausen (born January 16,1801; died May 23,1885) was a Danish mathematician and astronomer. He discoverd a factor of the sixth Fermat number (1854).