Fibonacci also described the method of "casting out the nines" (to check the accuracy of arithmetical calculations) in his book "Liber Abaci" in 1202. Seehttp://www.significancemagazine.org/details/webexclusive/1382001/One-sma...

## Fibonacci's "Liber Abaci" and "casting out the nines"

Fibonacci also described the method of "casting out the nines" (to check the accuracy of arithmetical calculations) in his book "Liber Abaci" in 1202. See

http://www.significancemagazine.org/details/webexclusive/1382001/One-sma...