北师大四年级数学下册小数乘法简便计算35211复习课程

四年级 下册 数学七年级下册拔高题下载二年级下册除法运算下载七年级下册数学试卷免费下载二年级下册语文生字表部编三年级下册语文教材分析 小数练习题一、脱式计算，能简算的要简算。7.8×1.3+0.948-1.8×240.25×0.46×0.42.5×1.3+0.93.8×41-3.8（4+0.4）×2.50.27×3.8+0.27×6.22.9×100.127.5×101-27.540×0.63×0.253.62×25.7+3.62×74.30.25×4.87×418.8+23.6+26.410.95-3.74-4.2695.59-（9.59+12.78）25.6-(0.23+5.6)-1.7713.75-(4.75+6.48)7.83+2.34-0.83+6.663.82+2.9+0.18+9.15.93+0.19+2.8125.48-((9.4-0.52)3.07-0.38-1.6235.6-1.8-15.6-7.27.3+2.7-7.3+2.748.4+2.78+51.6-0.7823.4+0.8-13.4-7.24.8+8.63+5.2+0.373.25+2.76+1.751.27+3.9+0.73+15.15.84-1.8-3.2132.44-(58.74+19.44)7.5+4.8-6.57.14-0.53-2.4713.75-(3.75+6.48)13.45-4.68+2.5547.8-7.45+8.236.8-4.5+6.9849.8-9.6+8.815.2-6.8-3.451.76+0.65+3.240.134+2.66+0.87.5+4.9-6.33.45+1.79+0.654.85+8.63+0.371.76+3.44+0.3536.54-1.76-8.668-2.45-1.0223.4+3.4-0.236.02+3.6+1.983.07-0.38-1.627.5+4.9-6.536.8-3.9-6.883.285+1.79+0.5923.4-0.8+13.432+4.9-8.61.29+3.7+2.715.93+0.49+2.069-2.45-1.6521+0.56+11.364.89-7.88-13.6二、能简易的要简易计算。12.5×8.2×80.23×1.4＋0.23×8.60.125×（80＋0.8）0.4×0.16×2.515.6×1017.85×991.15×99＋1.1516.2×101－16.245×0.78＋5.5×7.82.8+7.2×0.810.34×2.5×0.41.25×11×4×0.88.93×5.7＋8.93×3.3＋8.934.82×1020.7×0.46+0.7×0.545.6-4.34+7.34685.7-（15.3-4.8）25.4-（15.3+7.7）3.6－1.28＋3.093.8-0.46-1.72325.6-(0.23+5.6)-1.7713.75-(4.75+6.48)7.83+2.34-0.83+6.663.82+2.9+0.18+9.125.48-((9.4-0.52)35.6-1.8-15.6-7.25.93+0.19+2.817.3+2.7-7.3+2.73+5.2+0.373.07-0.38-1.6248.4+2.78+51.6-0.7823.4+0.8-13.4-7.24.8+8.61.27+3.9+0.73+15.15.84-1.8-3.2132.44-(58.74+19.44)7.5+4.8-6.513.45-4.68+2.553.25+2.76+1.7513.75-(3.75+6.48)7.14-0.53-2.4747.8-7.45+8.236.8-4.5+6.9849.8-9.6+8.815.2-6.8-3.453.45+1.79+0.653.45+1.79+0.651.76+0.65+3.240.134+2.66+0.87.5+4.9-6.34.85+8.63+0.371.76+3.44+0.3536.54-1.76-8.663.45+1.79+0.657.5+4.9-6.523.4+3.4-0.236.02+3.6+1.983.07-0.38-1.6236.8-3.9-6.883.285+1.79+0.5923.4-0.8+13.41.29+3.7+2.7121+0.56+11.332+4.9-8.65.93+0.49+2.069-2.45-1.65一、乘法互换律2abcacb0.25×8.5×412.5×0.96×0.80.25×0.73×40.25×16.2×4二乘法联合律（ab）ca（cb）4.36×12.5×80.95×0.25×435×0.2×0.50.75×50×0.4三、乘法分派律(ab)cacbc(1.25－0.125)×8（20－4）×0.25(2+0.4)×5（125+2.5）×0.8四、乘法分派律逆应用abaca(bc)3.72×3.5＋6.28×3.515.6×2.1－15.6×1.13.83×4.56＋3.83×5.447.09×10.8－0.8×7.0927.5×3.7－7.5×3.73.9×2.7＋3.9×7.310.6×0.35－9.6×0.357.6×0.8＋0.2×7.6五、把此中一个因数分红两个数的和或差，再按乘法分派律0.8×100.10.79×990.85×1993.65×10.14.6×0.90.65×1014.8×10.13.6×1020.39×1998.9×1.010.32×4033.65×10.10.85×9.90.65×101六、拆分因数1.25×2.5×323.2×0.25×12.50.25×3625×4.48.8×1.25七、增添因数“1”56.5×99＋56.59.7×99＋9.74.2×99＋4.25.4×11-5.431.87×9.9＋0.18712.7×9.9＋1.27八、改正因数的小数点地点6.66×3.3+66.6×6746×57＋23×864.8×7.8＋78×0.523.14×0.68＋31.4×0.032101×0.87-0.91×873.65×4.7－36.5×0.372.3×16+2.3×23+2.3314×0.043＋3.14×7.2－31.4×0.155×1.03×0.232×1.250.45×9953×10.10.125×9612.5×10.825×7.3×0.445×21－50×2.145×1.58＋5.5×15.84.2×6.51＋3.49×4.29.99×2.22＋3.33×3.34三、直接写得数3.8×2=10×0.7=13.9×0=50.8×100=5.5×1=1.8×0.5=3.2×3=13.1×0.3=0.08×1.25=2.5×4=2.5×8=0.5×0.2=0.6×0.1=0.7×0.8=2.5×8×0=125×0.8=3.8×2=10×0.7=13.9×0=508÷100=5.5×1=1.8×0.5=3.2×3=13.1×0.3=0.08×1.25=2.5×4=2.5×8=0.5×0.2=0.6×0.1=0.7×0.8=2.5×8×0=125×0.8=四、竖式计算2.8×0.7=13×0.15=0.39×0.6=0.38×600=7.05×2.4=0.46×7.9=89.3×7.6=60.5×400=3.05×18=4.6×18.9=40.5×4.2=0.37×2.31=43.8×0.12=0.57×0.6=6.4×0.5=6.7×5.8=9.8×3.8=7.8×6.4=4.6×2.7=4.5×2.7=5×1.6=3×0.6=3×1.2=6.7×7.6=5.4×7.8=2.6×3.6=3.5×1.7=8.3×2.6=1.4×0.7=4.5×2.8=7.4×2.6=6.2×1.4=5.4×2.6=2.3×1.4=3.7×1.8=4.5×2.3=5.2×1.6=3.6×0.8=0.66×1.4=6.5×5.8=0.72×0.49=0.42×0.28=0.24×0.19=2.4×1.3=0.72×0.27=0.78×0.32=0.65×0.04=0.23×0.16=0.29×0.15=0.16×0.19=4×1.2=7×4.6=6×0.37=0.28×0.27=0.75×0.42=2.3×1.9=8×0.64=2.7×0.8=10×4.2=7.1×3.9=4.3×1.4=2.6×1.6=0.8×0.3=0.65×0.4=0.91×0.6=1.8×1.6=4.8×0.5=3.2×0.4=9.8×4.8=12×8.3=15.2×6.5=20.1×11.1=13.34×10.32=6.52×0.48=6.3×5.1=8.7×3.6=14.3×4.3=1.5×0.54=10×4.2=2.47×3.24=2.98×0.56=5.64×1.78=8.02×0.98=7.1×3.9=2.8×11.39=12.53×4.67=7.2×6.45=1.65×3.35=7.96×1.45=60×1.27=6.07×4.89=5×0.41=0.9×0.5=2×0.7=1.2×4.3=5.4×2.7=6×2.9=3.7×1.7=4.2×0.8=7.5×2.5=52.2×4.3=9.5×7.1=3.5×1.6=5.2×2.8=7.8×1.6=9.6×4.1=10×4.2=5.1×2.5=4.1×3.4=1.2×3.8=9.6×4.1=7.8×1.6=3.5×1.6=4.4×1.4=2.9×2.1=3.5×1.2=4.8×3.4=6.9×2.5=2.5×7.8=8×5.4=6.9×2.5=2×3.5=6.8×2.2=4.7×5.4=4.1×8.8=2.2×5.5=9.6×2.1=1.7×3.8=7.4×3.6=0.8×0.23=1.6×2.4=4.7×3.5=1.2×3.6=1.5×3.8=2.8×1.2=7.3×2.7=7.3×2.7=6.2×3.7=4.2×3.9=0.54×0.65=7.5×5.2=0.7×0.5=0.32×0.47=8.3×6.3=7.2×0.42=0.48×0.52=0.8×0.25=43.5×0.65=0.32×0.16=0.35×0.55=0.87×0.8=0.24×0.08=0.92×0.37=1.4×0.6=3.6×4.2=0.72×0.48=6.8×3.2=7.1×3.4=0.42×0.66=0.32×0.68=2.8×7.2=0.65×0.19=3.09×1.2=3.25×5.64=0.25×0.47=0.82×0.18=7.8×2.4=0.45×0.18=0.4×0.16=8.2×1.8=0.73×0.27=8×3.2=9.8×4.8=3×2.4=2.8×0.9=1.29×0.18=5.1×0.8=10×0.3=8.9×4.9=6.8×0.7=8×0.72=6.6×3.4=6.4×1.3=1.2×0.8=7.3×6.2=8.7×3.6=12.3×0.7=0.8×9.2=4.7×1.9=5.1×3.9=1.4×0.6=63.8×6.4=0.6×7.45=4.9×0.1=4.5×3.2=1.8×0.9=6.5×0.5=10.5×6.5=7.5×0.5=0.78×0.28=12.8×2.8=9.6×2.3=3.8×0.12=0.8×0.08=10×7.4=7.5×3.2=0.42×0.58=0.8×0.15=2.5×0.4=8.2×2.6=1.4×0.7=2.5×4.6=0.5×9.8=6.7×2.6=7.2×5.9=8.7×3.6=5.69×2.48=2.9×4.1=9.1×6.7=2.03×1.2=8.6×4.9=1.3×2.03=9.46×7.21=1.56×2.24=3.5×1.25=0.75×0.4=20×0.78=4.8×4.2=5.7×3=4.9×1.7=1.34×0.8=2×0.75=8.7×0.03=0.2×0.09=8.5×2.5=3.4×1.4=0.68×0.42=7.82×7.2=2×9.1=0.48×0.52=8.1×5.1=0.78×0.24=0.8×0.18=0.89×0.25=1×0.98=0.9×0.1=1×0.8=4.5×4=5.6×4=5.7×3.3=10×4.4=6×6.6=9.5×2.7=1×0.55=五、列式计算。1、甲数是15.24，比乙数多7.6，乙数是多少？2、3．58加上7.08与5.1的差，和是多少？六、解决问题。1、小红用20元钱买文具，买钢笔用去6.7元，买文具盒用去9.8元，还剩下多少钱？2、爸爸用两条长度分别是1.27米、1.35米的绳索接起来捆扎报纸。接口处共用去绳索0.25米，接好后的绳索有多长？73、一桶油连桶共重12.65千克，用去一半后，连桶还重6.85千克，本来的桶里有油多少千克？二、减法中的巧算1.减法的性质：a-b-c=a-（b+c）巧算下边各题：①300-73-27②7.42-(3.42+1.5)③4723-（723＋189）三、加减混淆式的巧算1.去括号和添括号的法例在只有加减运算的算式里，假如括号前面是“＋”号，则无论去掉括号或添上括号，括号里面的运算符号都不变；假如括号前面是“-”号，则无论去掉括号或添上括号，括号里面的运算符号都要改变，“+”变“-”，“-”变“+”，即：a＋（b＋c＋d）＝a＋b＋c＋da-（b＋a＋d）＝a-b-c-da-（b-c）＝a-b+c2.带符号“迁居”325＋46-125＋54=325-125＋46+54=（325-125）+（46＋54）=200+100＝300注意：每个数前面的运算符号是这个数的符号.如+46，-125，+54.而325前面虽然没有符号，应看作是+325。找“基准数”法几个比较靠近于某一整数的数相加时，选这个整数为“基准数”。计算78+76＋83＋82+77＋80＋79＋85二、用简易方法计算：536+（541+464）+459588＋264＋1488996＋3458＋75464995-（995-480）1870-280-5204250-294＋94478-128+122-72464-545＋99+345537-（543-163）-57947+（372-447）-572小数乘法的简易运算一、乘法互换律与联合律的运用。提示1：以下计算中，有的需要把一个小数拆成两个数相乘，要注意拆分后两数8相乘的大小应当与原数相等，特别是小数的位数。如3.2=0.8×43.2=0.4×80.32=0.04×80.32=0.08×45.6=0.8×75.6=0.7×80.56=0.07×80.56=0.08×70.48=0.12×40.48=0.04×12提示2：应用乘法联合律解题的口诀是连乘用联合提示3：应用乘法联合律解题的格式是a×b×c=a×(b×c)最后一个步骤是“×”，不要当作是“+”.如2.5×0.48=2.5×0.04×12=0.1×12=1.24.56×0.4×2.512.5×2.7×0.812.5×3.2×0.252.5×0.4812.5×5.625×0.36乘法分派律的运用。提示1：A组中的一个因数都具备一个特色，都靠近整数1、10、100等，这样的数就能够拆分红两个数相加或许相减。如10.4=（10+0.4）9.9=(10-0.9)0.99=(10-0.01)但也有这样的数8.8=（8+0.8）4.4=(4+0.4)0.48=(0.4+0.08)提示2：应用乘法分派律解题的口诀是乘加乘减用分派提示3：应用乘法分派律解题的格式是（a+b）×c=a×c+b×c最后一个步骤是“+”，不要当作是“×”.如2.5×0.48=2.5×(0.4+0.08)=2.5×0.4+2.5×0.08=1+0.2=1.2不是=1+0.2=2提示4：应用乘法分派律解题的最后一步，有时是数字比较大的两个数相加减，口算简单犯错，这时就要打底稿竖式计算。0.25×10.412.5×8.89.9×0.353.7×1.8－2.7×1.895.7×0.28＋6.3×0.28－0.28×21.08×9＋1.089比较乘法联合律与分派律在简易运算时的差别。下边各题用两种方法简算。12.5×8.812.5×8.80.25×4.80.25×4.8二、变一变，能简算。48×0.56＋44×0.48表面上看来，左右两边没有同样的因数，不可以使用乘法分派律。我来试一试：0.279×343＋0.657×2790.264×519＋264×0.4819.16×1.53－0.053×91.6三、拓展提升。99.99×0.8＋11.11×2.8314×0.043＋3.14×7.2－31.4×0.15小数除法的简易运算小数除法的简易计算与整数除法的简易计算同样，用到的是除法性质。除法性质1、A÷B÷C=A÷(B×C)如：42÷2.8=42÷（0.7×4）=42÷0.7÷4=60÷4=15如：420÷2.5÷4=420÷（2.5×4）=420÷10=42除法性质2、(a－b)÷c=a÷c－b÷c除法性质3、A÷(B÷C)=A÷B×C除法性质4、A×(B÷C)=A×B÷C小数乘除法的递等式计算小数乘除法的递等式计算方法与整数的同样，能简易的要简易，但也有的是不可以简易比方：3.6+6.4×0.5不可以掉进先加后乘的圈套里。3.6×5+15×6.4不可以掉进应用乘法分派率的圈套里。1073.8－1.64－13.8－5.3666.86－8.66－1.340.25×16.2×43.72×3.5＋6.28×3.536.8－3.9－6.125.48－(9.4－0.52)4.8×7.8＋78×0.523.6×1026.4×0.25＋3.6÷432＋4.9－0.94.8－4.8×0.5(1.25－0.125)×84.8×100.156.5×9.9＋56.57.09×10.8－0.8×7.094.02＋5.4＋0.985.17－1.8－3.213.75－(3.75＋6.48)3.68＋7.56－2.687.85＋2.34－0.85＋4.6635.6－1.8－15.6－7.23.82＋2.9＋0.18＋9.19.6＋4.8－3.67.14－0.53－2.475.27＋2.86－0.66＋1.6313.35－4.68＋2.6547.8－7.45+8.80.398+0.36+3.6415.75+3.59－0.59+14.2542.5－(6.07＋1.13)4.2÷3.5320÷1.25÷818.76×9.9＋18.763.52÷2.5÷0.44.78÷0.2＋3.443.9－4.1＋6.1－5.90.49÷1.41.25×2.5×323.6－0.6×23.65×10.13.6－3.6×0.815.2÷0.25÷4115.6÷3.59.6÷0.8÷0.44.2×99＋4.20.89×100.1146.5－(23＋46.5)17.8÷(1.78×4)5.83×2＋4.27(45.9－32.7)÷8÷0.1259.7×99＋9.74.36×12.5×815.6×13.1－15.6－15.6×2.10.65×10127.5×3.7－7.5×3.78.54÷2.5÷0.43.83×4.56＋3.83×5.446048＋975-3045498×396048＋75-3005648×75-30056098＋935-1045404×24－7581048＋975-345640×75÷35878×2968×975-3459948＋275-3045690×6÷3568＋975-34568＋975÷345648＋75-35685＋975-34568＋975-345548×975-304548×975-3046748＋975-50456048＋975-30450.425×0,38÷0,011220.5-1.074-8.35×5.5748＋95-4548×975-30450.425×0,38÷0,0120.5-1.074-8.35×5.552.8÷0.75×0.2545×（267＋143）（2448＋864）÷23327＋9664÷32×25727＋9660÷30×25586-45×81÷2758-45×80÷253.68÷4.6＋6.32368÷46＋632604×24－758644×14－858604×24－758408×59478×39278×39478×1910.8/15+7/3-8/5408－12×24（46＋28）×6042×50－1715÷532＋105÷5（108＋47）×52420×（327－238）(4121+2389)÷7671×15-97413469×12+1492405×(3213-3189)5000-56×23125×(97-81)6942+480÷3304×32-15420+80÷4-2025×4-12×5100÷（32-30）×070×〔（42-42）÷18〕75×65+75×351415