Comment They were two millenia late to the party. (Score 1) 170
There are several algorithms using the binary number system, including left-to-right binary exponentiation, in Pingala's Chanda-sutra, before 200 BCE. Knuth's _The Art of Computer Programming, Volume 2: Seminumerical Algorithms_ cites B. Datta and A.N. Singh's 1935 _History of Hindu Mathematics 1_.
Also al-Kashi described the right-to-left binary exponentiation algorithm in 1427 CE.