It is unfortunate that it took centuries after al-Khowrizmi before zero was commonly understood and used. Al-Khowrizmi did know zero from the Hindu numeral system but did not use it as proofs when given "had to be geometric to be convincing" (Burton, D. M., 2011, p. 240). Perhaps, it is this geometric view that delayed the development of algebra and other abstract ideas. Burton also informs that it was Fibonacci's Liber Abaci (Book of Counting) in 1202 and its examples that made calculations easy with the "zero" placeholder but this was in the context of real-world applications. Still, mathematical ideas and interest wasn't accessible until printing was invented around 1450. And even then Liber Abaci wasn't printed until 1857.MstoneMTH314 (talk) 06:58, 2 May 2011 (UTC)