8. How old was Newton when he became Lucasian Professor of Mathematics at Cambridge?
From Quiz Sir Isaac Newton's Life
Answer: 27 years old
Isaac Barrow became Cambridge's first Lucasian Professor of Mathematics in 1664. The colleges of Cambridge closed during the plague months of 1665-1666, and Newton returned to Woolsthorpe, where he did much of his serious work on optics, light, and motion. In 1667, when he returned to Trinity, he was elected as a Trinity Fellow. He helped edit Barrow's lectures on optics for publication in 1669, but he did not tell Barrow that his own experiments proved much of Barrow's findings obsolete. (Newton had not yet made his own work known). Barrow resigned in 1669, and he recommended Newton, then twenty-seven, as his replacement. On Oct. 29, 1669 Newton became Cambridge's second Lucasian Professor of Mathematics.