Infinity Warning: You are not logged in. Your IP address will be publicly visible if you make any edits. If you log in or create an account, your edits will be attributed to your username, along with other benefits.Anti-spam check. Do not fill this in! ===17th century=== In the 17th century, European mathematicians started using infinite numbers and infinite expressions in a systematic fashion. In 1655, [[John Wallis]] first used the notation <math>\infty</math> for such a number in his ''De sectionibus conicis'',<ref>{{Cite book|url=https://books.google.com/books?id=OQZxHpG2y3UC&q=infinity|title=A History of Mathematical Notations|last=Cajori|first=Florian|publisher=Cosimo, Inc.|year=2007|isbn=9781602066854|volume=1|pages=214|language=en}}</ref> and exploited it in area calculations by dividing the region into [[infinitesimal]] strips of width on the order of <math>\tfrac{1}{\infty}.</math><ref>{{harvnb|Cajori|1993|loc=Sec. 421, Vol. II, p. 44}}</ref> But in ''Arithmetica infinitorum'' (1656),<ref>{{Cite web |title=Arithmetica Infinitorum |url=https://archive.org/details/ArithmeticaInfinitorum/page/n5/mode/2up}}</ref> he indicates infinite series, infinite products and infinite continued fractions by writing down a few terms or factors and then appending "&c.", as in "1, 6, 12, 18, 24, &c."<ref>{{harvnb|Cajori|1993|loc=Sec. 435, Vol. II, p. 58}}</ref> In 1699, [[Isaac Newton]] wrote about equations with an infinite number of terms in his work ''[[De analysi per aequationes numero terminorum infinitas]]''.<ref>{{cite book |title=Landmark Writings in Western Mathematics 1640-1940 |first1=Ivor |last1=Grattan-Guinness |publisher=Elsevier |year=2005 |isbn=978-0-08-045744-4 |page=62 |url=https://books.google.com/books?id=UdGBy8iLpocC |url-status=live |archive-url=https://web.archive.org/web/20160603085825/https://books.google.com/books?id=UdGBy8iLpocC |archive-date=2016-06-03 }} [https://books.google.com/books?id=UdGBy8iLpocC&pg=PA62 Extract of p. 62]</ref> Summary: Please note that all contributions to Christianpedia may be edited, altered, or removed by other contributors. If you do not want your writing to be edited mercilessly, then do not submit it here. You are also promising us that you wrote this yourself, or copied it from a public domain or similar free resource (see Christianpedia:Copyrights for details). Do not submit copyrighted work without permission! Cancel Editing help (opens in new window) Discuss this page