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1、速算珠心算心算口算珠算（Quickabacusmentalarithmeticabacusmentalarithmetic）Quick
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4、mentalabacusmentalarithmeticabacus??1.dozenbyten:Aheadbyhead,tailandtail,tailtotail.Example:12x14=?Solution:1x1=124=62x4=812x14=168Note:onebitmultiplicationisnotenough.Twodigitsshouldbeoccupiedby0.2.headsareid
5、entical,andtailsarecomplementary(tailequals10):1formula:ahead,headbyhead,tailtotail.Example:23x27=?Solution:2+1=32x3=63x7=2123x27=621Note:onebitmultiplicationisnotenough.Twodigitsshouldbeoccupiedby0.3.thefirstmultiplierscomplementeachother,andtheothermultipliernumbersthesame:1fo
6、rmula:ahead,headbyhead,tailtotail.Example:37x44=?Solution:3+1=44x4=167x4=2837x44=1628Note:onebitmultiplicationisnotenough.Twodigitsshouldbeoccupiedby0.4.bydozensofdozens:Aheadbyhead,headandtailtotailhead.Example:21x41=?Solution:2x4=82+4=61x1=121x41=8615.11multipliedbyanynumber:F
7、ormula:bothrealwhereabouts,middleanddrop.Example:11x23125=?Solution:2+3=53+1=41+2=32+5=72and5areatthebeginningandtheendrespectively11x23125=254375Note:enterwithfullten.6.,tenmultipliedbyanynumber:Formula:secondmultiplierfirsttrendfalling,afactorbehindthefirstsecondmultipliedbyth
8、efactorofeachnumber,plusadigittofall.Example:13x326=?Solution:the13bitis33x3+2=113x2+6=123x6=1813x326=4238Note:enterwithfullten."Withthefirstendandtheten"and"endwiththefirstandten"algorithm.Theso-called"withthefirstandtheendoftheten",referstothetwodigitmultiplication,tendigits,a
9、digitsumof10,forexample,67x63,tendigitis6,a7+3andjustequaltothe10,Itoldhim,suchasdigitalmultiplicationisinfact.Thelaw.Istheproductofthenumberofdigitsaftertwodigits,lessthan10ofthetendigitsonthe0;oneplus1multipliedbytenforthesamenumberofresults,isonethousandandonehundred.Specific
10、totheexampleabove67x63,7x3=21,twothisisthenumber21;6*=6*7=42(6+1),the42isthenumberofthetoptwo,together,67*63=4221.Similarly,15x15=225,89x81=7209,64x66=4224,92x98=9016.Theso-called"endwiththefirstandten",twonumbersaremultiplied,anumberofidentical,tendigitsumofjust10,forexample,45
11、x65,twobitsare5,tendigit4+6resultsisequalto10.I
