Sifuri

Sifuri (au sufuri kutoka Kiarabu sifr iliyotafsiri neno la Kisanskrit sunya lenye maana ya mahali patupu) ni namba ya pekee ambayo haina thamani peke yake, mpaka iandikwe baada ya namba nyingine yoyote: hapo inazidisha thamani yake mara kumi. Kwa kawaida inaandikwa 0 lakini ٠ kwa namba za Kiarabu.

Kwa Kiswahili namba hiyo inaitwa pia ziro kutokana na neno hilohilo la Kiarabu lakini kwa kupitia Kiitalia, Kifaransa na hatimaye Kiingereza (inapoandikwa zero).

Sifuri kama namba ilianza kutumika India kabla ya karne ya 9 BK, pengine hata karne ya 3.

 Tanbihi 

 Marejeo 

 Amir D. Aczel (2015) Finding Zero, New York City: Palgrave Macmillan. ISBN 978-1-137-27984-2
 Barrow, John D. (2001) The Book of Nothing, Vintage. ISBN 0-09-928845-1.
Diehl, Richard A. (2004) The Olmecs: America's First Civilization, Thames & Hudson, London.
Ifrah, Georges (2000) The Universal History of Numbers: From Prehistory to the Invention of the Computer, Wiley. ISBN 0-471-39340-1.
Kaplan, Robert (2000) The Nothing That Is: A Natural History of Zero, Oxford: Oxford University Press.
 Seife, Charles (2000) Zero: The Biography of a Dangerous Idea, Penguin USA (Paper). ISBN 0-14-029647-6.
 Bourbaki, Nicolas (1998). Elements of the History of Mathematics. Berlin, Heidelberg, and New York: Springer-Verlag. ISBN 3-540-64767-8.
 Isaac Asimov (1978). Article "Nothing Counts" in Asimov on Numbers. Pocket Books.

 Viungo vya nje 

 Search for the world's first zero leads to the home of Angkor Wat
 A History of Zero 
 Zero Saga
 The History of Algebra 
 Edsger W. Dijkstra: Why numbering should start at zero, EWD831 (PDF of a handwritten manuscript)
 "My Hero Zero"  Educational children's song in Schoolhouse Rock!