He was 43 years old in the year 1849 =. Hence, he was born in the year 1849 - 43 = 1806. -------------------- Augustus De Morgan (27 June 1806 – 18 March 1871) was a British mathematician and logician. He formulated De Morgan's laws and introduced the term mathematical induction, making its idea rigorous. See this Wikipedia article : https://en.wikipedia.org/wiki/Augustus_De_Morgan