Editing Subtraction (section)

===In America===
Almost all American schools currently teach a method of subtraction using borrowing or regrouping (the decomposition algorithm) and a system of markings called crutches.<ref name="Klapper1916">{{cite book |author=Klapper |first=Paul |url=https://archive.org/details/teachingarithme00klapgoog |title=The Teaching of Arithmetic: A Manual for Teachers |year=1916 |pages=[https://archive.org/details/teachingarithme00klapgoog/page/n94 80]– |author-link=Paul Klapper |access-date=2016-03-11}}</ref><ref>Susan Ross and Mary Pratt-Cotter. 2000. "Subtraction in the United States:  An Historical Perspective," ''The Mathematics Educator'' 8(1):4–11. p. 8: "This new version of the decomposition algorithm [i.e., using Brownell's crutch] has so completely dominated the field that it is rare to see any other algorithm used to teach subtraction today [in America]."</ref> Although a method of borrowing had been known and published in textbooks previously, the use of crutches in American schools spread after [[William A. Brownell]] published a study—claiming that crutches were beneficial to students using this method.<ref>{{cite journal |title=Subtraction From a Historical Perspective |journal=School Science and Mathematics |year=1999 |last1=Ross |first1=Susan C. |last2=Pratt-Cotter |first2=Mary |volume=99 |issue=7 |pages=389–93 |doi=10.1111/j.1949-8594.1999.tb17499.x }}</ref> This system caught on rapidly, displacing the other methods of subtraction in use in America at that time.