Ahmed
# Ahmed ibn Yusuf

### Born: 835
in Baghdad (now in Iraq)

Died: 912
in Cairo, Egypt

**Ahmed ibn Yusuf** wrote on ratio and proportion and it was translated into Latin by Gherard of Cremona. The book is largely a commentary on, and expansion of, Book 5 of Euclid's Elements .
Ahmed ibn Yusuf also gave methods to solve tax problems which appear in Fibonacci's Liber Abaci . He was also quoted by Bradwardine, Jordanus and Pacioli.

**References (2 books/articles)**

JOC/EFR December 1996