context: Emanuel Lasker (German: Emanuel Lasker, in Russian sources the name is often written as Emanuel; December 24, 1868 - January 11, 1941) - German chess player and mathematician, representative of a positional school, second world chess champion ( 1894-1921 </ b >). Lasker retained the title of world champion for twenty-seven years, a record achievement for chess, and continued to perform at the highest level until he was 68.
question: When did the German chess player and mathematician Emanuel Lasker become the world chess champion?
answers.text: 1894-1921