Pietro Cataldi

Pietro Cataldi was an Italian mathematician, born in Bologna on 15 April 1552 and died there on 11 February 1626. He was educated in Bologna and began teaching mathematics at seventeen, choosing to teach in the local Italian dialect rather than Latin so that more people could benefit. He taught at the Academy of Design in Florence and in Perugia, where he lectured at the university from 1572, then returned to Bologna in 1584 and taught mathematics and astronomy at the Studio di Bologna for almost forty years. He wrote around thirty books, among them the four part Practica aritmetica of 1602 to 1617. He is best known for work on perfect numbers and continued fractions. In 1603 he showed that two to the n minus one can be prime only when n is prime, found that it is prime for n equal to 17 and 19, and so identified the sixth and seventh perfect numbers. His 1613 treatise on square roots is an early investigation of continued fractions.