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1、六上奥数培优分数乘法简便计算一、例题精讲2.3.5吗:+4+1II33211H71172016+2017x201520162017-1.15.102+102X100101X10216.221-+321-+421-17.29II19.1.25-+1-1-1.25-994320.-9+-1588103一-8521.3.75X7351X5730+16.2X62.5822.200*2007x200920092008201020082009-1.20092010-1.一、例题精讲1 ZX2734=(1一上)273427=2734=23. (*+8+6:+6)(3-=(彳+6;+8:+6:)3-=263+
2、2613=78+2=80314. 15X-117=(14+1)-117=14-+-7117=2+11一2三6b22+1.x1.1.+123=-22+-11+-x2777=I(22+22+6)502.-27+-3944=-27+-X(2712)44=(-+-)27+-12444=27+3=30H)5.13-X-+16-X-+15X-344556:(12+1-)-+(1S+1-)-+(18+1-)-344S56=91+12+1+15+1=39201.6+2tH7201520162017-1.2017+2017x2015-。20162017-1.2()17(2015+1一】20162017-1.-2
3、0172006-1.20162017-1.二、课堂小测38101158.一X429.1110.-45+-1541100266=X(41+1)101=(1002-1)X=-45+-754110026638一9R4.-I01101-iV1O一TXIZU411002638一901=38=100=20411002=12+15X-+14+20-137137=(12+14)X5+15+20)I=26x+35=2+S=713.13-+15-+13-233756=(12+-)-+(14+-)-+(12+-)-233756102+102。100101X102102+102X1.OOIO1.XIO2102(100
4、+1)101X102102X101101X102=8+1+10+-+10+116.22Xg+3?X1;+42XC34S=2z-+32-+42-234=23+34+45=6+12+2017.292=(30-I=(12-73)(4-20107=(1210)(4-20107=(12定)X(4-:)20107=-(4-)47=619.1.25-1-1-1.2S-9943=1.25彳+WT=1.25(1-)=1.2521.3.75735-5730+16.262.58=3.75735-0.3755730+16.262.5=3.75735-3.75573+1626.25=3.75162+1626.25=162020082009-1.20092010-1.222008-2007x20092009200820102009-2007X2009-120082009-1.201020082010-1.20092010-12008x2009-12008X2009-12009X2OIoT20092010-1.