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...
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...