北师大版四年级下册小数简便运算
（完整版）北师大四年级数学下册小数乘法简便计算
（完整版）北师⼤四年级数学下册⼩数乘法简便计算四年级下册⼩数练习题⼀、脱式计算，能简算的要简算。
7.8×1.3+0.9 48-1.8×24 0.25×0.46×0.42.5×1.3+0.93.8×41-3.8 （4+0.4）×2.50.27×3.8+0.27×6.2 2.9×100.1 27.5×101-27.540×0.63×0.25 3.62×25.7+3.62×74.3 0.25×4.87×418.8+23.6+26.4 10.95-3.74-4.26 95.59-（9.59+12.78）25.6-(0.23+5.6)-1.77 13.75-(4.75+6.48) 7.83+2.34-0.83+6.66 3.82+2.9+0.18+9.1 5.93+0.19+2.81 25.48-((9.4-0.52)3.07-0.38-1.62 35.6-1.8-15.6-7.2 7.3+2.7-7.3+2.7 48.4+2.78+51.6-0.78 23.4+0.8-13.4-7.24.8+8.63+5.2+0.373.25+2.76+1.75 1.27+3.9+0.73+15.1 5.84-1.8-3.2 132.44-(58.74+19.44) 7.5+4.8-6.57.14-0.53-2.47 13.75-(3.75+6.48) 13.45-4.68+2.55 47.8-7.45+8.2 36.8-4.5+6.98 49.8-9.6+8.8 15.2-6.8-3.45 1.76+0.65+3.240.134+2.66+0.8 7.5+4.9-6.3 3.45+1.79+0.65 4.85+8.63+0.371.76+3.44+0.35 36.54-1.76-8.66 8-2.45-1.02 23.4+3.4-0.23 6.02+3.6+1.98 3.07-0.38-1.62 7.5+4.9-6.5 36.8-3.9-6.88 3.285+1.79+0.59 23.4-0.8+13.4 32+4.9-8.6 1.29+3.7+2.715.93+0.49+2.06 9-2.45-1.65 21+0.56+11.3 64.89-7.88-13.6⼆、能简便的要简便计算。
北师大四年级数学下册小数乘法简便计算
精心整理四年级下册小数练习题一、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）×2.50.27×40×6二、能简便的要简便计算。
12.5×8.2×80.23×1.4＋0.23×8.60.125×（80＋0.8）0.4×0.16×2.55.6×1017.85×991.15×99＋1.1516.2×101－16.245×0.78＋5.5×7.82.8+7.2×0.81???0.34×2.5×0.4??1.25×11×4×0.8?8.93×5.7＋8.93×3.3＋8.93?4.82×102??0.7×0.46+0.7×0.54?5.6-4.34+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)-1.77???13.75-(4.75+6.48)?7.83+2.34-0.83+6.66??3.82+2.9+0.1 8+9.136.8-3.9-6.88???3.285+1.79+0.59????23.4-0.8+13.4?1.29+3.7+2.7121+0.56+11.332+4.9-8.65.93+0.49+2.06?????????9-2.45-1.65????? ??一、乘法交换律0.25×8.5×4??12.5×0.96×0.8?????0.25×0.73×4??0.25×16.2×4?二乘法结合律4.36×12.5×8???0.95×0.25×435×0.2×0.5???????0.75×50×0.4三、乘法分配律(1.25－0.125)×8（20－4）×0.25(2+0.4)×5（125+2.5）×0.83.72× 5.44??7.09×10.6×0.8×4.6×0.39×0.85×1.25×56.5×1.87×9.9＋0.187?12.7×9.9＋1.27八、更改因数的小数点位置6.66×3.3+66.6×67????????46×57＋23×86?4.8×7.8＋78×0.52??3.14×0.68＋31.4×0.032101×0.87-0.91×87?3.65×4.7?－36.5×0.372.3×16+2.3×23+2.3?????314×0.043＋3.14×7.2－31.4×0.155×1.03×0.232×1.25??0.45×99????53×10.1????0.125×96??12.5×10.8??25×7.3×0.4?45×21－50×2.1????45×1.58＋5.5×15.8?4.2×6.51＋3.49×4.2??9.99×2.22＋3.33×3.34三、直接写得数3.8×5.5×0.08×0.6×3.8×5.5×0.08×0.6×2.8×7.05×3.05×3.8××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××0.4=9.8××3.6=14.3×2.98××0.9×5.4×5.2×5.1× 2.1= 3.5×8×4.7×1.7×3.8=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=8×1.29×8.9×12.3××0.1=4.57.5×3.8××2.6=1.4××4.1= 9.1×9.46××8.5××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。
北师大四年级数学下册小数乘法简便计算
精心整理四年级下册小数练习题一、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）×2.50.27×40×6二、能简便的要简便计算。
12.5×8.2×80.23×1.4＋0.23×8.60.125×（80＋0.8）0.4×0.16×2.55.6×1017.85×991.15×99＋1.1516.2×101－16.245×0.78＋5.5×7.82.8+7.2×0.81???0.34×2.5×0.4??1.25×11×4×0.8?8.93×5.7＋8.93×3.3＋8.93?4.82×102??0.7×0.46+0.7×0.54?5.6-4.34+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)-1.77???13.75-(4.75+6.48)?7.83+2.34-0.83+6.66??3.82+2.9+0.1 8+9.136.8-3.9-6.88???3.285+1.79+0.59????23.4-0.8+13.4?1.29+3.7+2.7121+0.56+11.332+4.9-8.65.93+0.49+2.06?????????9-2.45-1.65????? ??一、乘法交换律0.25×8.5×4??12.5×0.96×0.8?????0.25×0.73×4??0.25×16.2×4?二乘法结合律4.36×12.5×8???0.95×0.25×435×0.2×0.5???????0.75×50×0.4三、乘法分配律(1.25－0.125)×8（20－4）×0.25(2+0.4)×5（125+2.5）×0.83.72× 5.44??7.09×10.6×0.8×4.6×0.39×0.85×1.25×56.5×1.87×9.9＋0.187?12.7×9.9＋1.27八、更改因数的小数点位置6.66×3.3+66.6×67????????46×57＋23×86?4.8×7.8＋78×0.52??3.14×0.68＋31.4×0.032101×0.87-0.91×87?3.65×4.7?－36.5×0.372.3×16+2.3×23+2.3?????314×0.043＋3.14×7.2－31.4×0.155×1.03×0.232×1.25??0.45×99????53×10.1????0.125×96??12.5×10.8??25×7.3×0.4?45×21－50×2.1????45×1.58＋5.5×15.8?4.2×6.51＋3.49×4.2??9.99×2.22＋3.33×3.34三、直接写得数3.8×5.5×0.08×0.6×3.8×5.5×0.08×0.6×2.8×7.05×3.05×3.8××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××0.4=9.8××3.6=14.3×2.98××0.9×5.4×5.2×5.1× 2.1= 3.5×8×4.7×1.7×3.8=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=8×1.29×8.9×12.3××0.1=4.57.5×3.8××2.6=1.4××4.1= 9.1×9.46××8.5××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。
北师大四年级数学下册小数乘法简便计算
四年级下册小数练习题一、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 ×6.2 2.9×100.127.5×101-27.540×0.63 ×0.25 3.62×25.7+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+6.66 3.82+2.9+0.18+9.1 5.93+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+2.7 48.4+2.78+51.6-0.7823.4+0.8-13.4-7.2 4.8+8.63+5.2+0.37 3.25+2.76+1.75 1.27+3.9+0.73+15.1 5.84-1.8-3.2 132.44-(58.74+19.44) 7.5+4.8-6.57.14-0.53-2.47 13.75-(3.75+6.48)13.45-4.68+2.5547.8-7.45+8.236.8-4.5+6.9849.8-9.6+8.815.2-6.8-3.45 1.76+0.65+3.240.134+2.66+0.87.5+4.9-6.3 3.45+1.79+0.65 4.85+8.63+0.371.76+3.44+0.3536.54-1.76-8.668-2.45-1.0223.4+3.4-0.23 6.02+3.6+1.98 3.07-0.38-1.627.5+4.9-6.5 36.8-3.9-6.88 3.285+1.79+0.5923.4-0.8+13.432+4.9-8.61.29+3.7+2.71 5.93+0.49+2.069-2.45-1.65 21+0.56+11.364.89-7.88-13.6二、能简便的要简便计算。
北师大四年级数学下册小数乘法简便计算
精心整理四年级下册小数练习题一、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）×2.50.27×40×6二、能简便的要简便计算。
12.5×8.2×80.23×1.4＋0.23×8.60.125×（80＋0.8）0.4×0.16×2.55.6×1017.85×991.15×99＋1.1516.2×101－16.245×0.78＋5.5×7.82.8+7.2×0.81???0.34×2.5×0.4??1.25×11×4×0.8?8.93×5.7＋8.93×3.3＋8.93?4.82×102??0.7×0.46+0.7×0.54?5.6-4.34+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)-1.77???13.75-(4.75+6.48)?7.83+2.34-0.83+6.66??3.82+2.9+0.1 8+9.136.8-3.9-6.88???3.285+1.79+0.59????23.4-0.8+13.4?1.29+3.7+2.7121+0.56+11.332+4.9-8.65.93+0.49+2.06?????????9-2.45-1.65????? ??一、乘法交换律0.25×8.5×4??12.5×0.96×0.8?????0.25×0.73×4??0.25×16.2×4?二乘法结合律4.36×12.5×8???0.95×0.25×435×0.2×0.5???????0.75×50×0.4三、乘法分配律(1.25－0.125)×8（20－4）×0.25(2+0.4)×5（125+2.5）×0.83.72× 5.44??7.09×10.6×0.8×4.6×0.39×0.85×1.25×56.5×1.87×9.9＋0.187?12.7×9.9＋1.27八、更改因数的小数点位置6.66×3.3+66.6×67????????46×57＋23×86?4.8×7.8＋78×0.52??3.14×0.68＋31.4×0.032101×0.87-0.91×87?3.65×4.7?－36.5×0.372.3×16+2.3×23+2.3?????314×0.043＋3.14×7.2－31.4×0.155×1.03×0.232×1.25??0.45×99????53×10.1????0.125×96??12.5×10.8??25×7.3×0.4?45×21－50×2.1????45×1.58＋5.5×15.8?4.2×6.51＋3.49×4.2??9.99×2.22＋3.33×3.34三、直接写得数3.8×5.5×0.08×0.6×3.8×5.5×0.08×0.6×2.8×7.05×3.05×3.8××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××0.4=9.8××3.6=14.3×2.98××0.9×5.4×5.2×5.1× 2.1= 3.5×8×4.7×1.7×3.8=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=8×1.29×8.9×12.3××0.1=4.57.5×3.8××2.6=1.4××4.1= 9.1×9.46××8.5××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。
北师大四年级数学下册小数乘法简便计算
四年级下册小数练习题一、脱式计算，能简算的要简算。
7.8×1.3+0.9 48-1.8×24 0.25×0.46×0.42.5×1.3+0.93.8×41-3.8 （4+0.4）×2.50.27×3.8+0.27×6.2 2.9×100.1 27.5×101-27.540×0.63×0.25 3.62×25.7+3.62×74.3 0.25×4.87×418.8+23.6+26.4 10.95-3.74-4.26 95.59-（9.59+12.78）25.6-(0.23+5.6)-1.77 13.75-(4.75+6.48) 7.83+2.34-0.83+6.66 3.82+2.9+0.18+9.1 5.93+0.19+2.81 25.48-((9.4-0.52)3.07-0.38-1.62 35.6-1.8-15.6-7.2 7.3+2.7-7.3+2.7 48.4+2.78+51.6-0.78 23.4+0.8-13.4-7.24.8+8.63+5.2+0.373.25+2.76+1.75 1.27+3.9+0.73+15.1 5.84-1.8-3.2 132.44-(58.74+19.44) 7.5+4.8-6.57.14-0.53-2.47 13.75-(3.75+6.48) 13.45-4.68+2.55 47.8-7.45+8.2 36.8-4.5+6.98 49.8-9.6+8.8 15.2-6.8-3.45 1.76+0.65+3.240.134+2.66+0.8 7.5+4.9-6.3 3.45+1.79+0.65 4.85+8.63+0.371.76+3.44+0.35 36.54-1.76-8.66 8-2.45-1.02 23.4+3.4-0.23 6.02+3.6+1.98 3.07-0.38-1.62 7.5+4.9-6.5 36.8-3.9-6.88 3.285+1.79+0.59 23.4-0.8+13.4 32+4.9-8.6 1.29+3.7+2.715.93+0.49+2.06 9-2.45-1.65 21+0.56+11.3 64.89-7.88-13.6二、能简便的要简便计算。
北师大四年级数学下册小数乘法简便计算
四年级下册小数练习题一、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 ×6.2 2.9×100.127.5×101-27.540×0.63 ×0.25 3.62×25.7+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+6.66 3.82+2.9+0.18+9.1 5.93+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+2.7 48.4+2.78+51.6-0.7823.4+0.8-13.4-7.2 4.8+8.63+5.2+0.37 3.25+2.76+1.75 1.27+3.9+0.73+15.1 5.84-1.8-3.2 132.44-(58.74+19.44) 7.5+4.8-6.57.14-0.53-2.47 13.75-(3.75+6.48)13.45-4.68+2.5547.8-7.45+8.236.8-4.5+6.9849.8-9.6+8.815.2-6.8-3.45 1.76+0.65+3.240.134+2.66+0.87.5+4.9-6.3 3.45+1.79+0.65 4.85+8.63+0.371.76+3.44+0.3536.54-1.76-8.668-2.45-1.0223.4+3.4-0.23 6.02+3.6+1.98 3.07-0.38-1.627.5+4.9-6.5 36.8-3.9-6.88 3.285+1.79+0.5923.4-0.8+13.432+4.9-8.61.29+3.7+2.71 5.93+0.49+2.069-2.45-1.65 21+0.56+11.364.89-7.88-13.6二、能简便的要简便计算。
北师大版四年级下册小数的混合运算和简便运算
个性化教学辅导教案学生姓名年级四年级学科数学上课时间教师姓名课题第9讲小数加减混合运算及简便计算教学目标1.结合生活实际创设问题情境，探索.发现并理解小数四则混合运算与整数四则混合运算的联系与区别，掌握小数四则混合运算顺序，能正确进行小数四则混合运算.2.培养学生良好的审题、计算、验算的习惯.3.体会小数四则混合运算在实际生活中的应用价值，从中获得价值体验，坚定学生学好数学的信心.教学过程教师活动学生活动1.说一说下面各题的运算顺序分别是怎样的?⑴12×5×3 ⑵ 30×7＋85 ⑶250×4－3202.说一说用到什么运算定律，才能使下面的计算简便?⑴ 25×98×4⑵ 125×5×8×4 ⑶ 15×201知识点一：小数的混合运算1.按照混合运算的运算法则计算下列各式.（1）2.6+1.4×1.5－1.5 （2）2.6+2.4×（1.4－1.05）（3）(31.8+3.2×4) × 5 （4）0.64×25×7.8+2.2知识点二：运用交换律简便运算2 . 用简便方法计算（1）0.8 ×3.2×12.5 （2）19.4×4×2.5 （3）0.4×0.7×0.25知识点三：运用结合律简便运算（1）2.55×7.1+2.45×7.1 （2）1437×27＋27×563（3）0.68×1.9+0.32×1.9（4）52×99+52知识点四：运用分配律简便运算（1）29×（10-0.1）（2）(0.123+123) ×100（3）31×99 (4) 25×10.1知识点一：小数加减法的计算法则小数点对齐，并把相同的数位对齐，末位算起，哪一位上的数满十向前一位进一；哪一位上的数不够减要向前一位借一再减.1.列竖式计算.8.65－6.31= 10－7.64= 16.39-6.47=13.21-9.38= 13.6＋8.46= 0.99＋1.1=2.脱式计算.3.6－1.28＋3.094.32－（1.26＋2.34）3.8×6.7+3.3×3.8 1.28×0.29-0.29×0.28 （4-0.4）×2.5101×4.8 56×12.5 3.45×79+3.450.4×4.6×251.25×0.41×16 1.08×99+1.081.计算.①（0.59+0.15）×0.12 ② 2.85 × 0.2 × 7.2 ③（8.6-1.7）×0.082.求近似值.①5.02 ×1.7（得数保留一位小数）②0.76 ×1.45 （结果精确到百分位）① 5.5×9.9 ②7.8 ×9+7.8 ③19.7× 5.3+ 4.7× 19.71.小数混合运算的顺序：在计算小数连乘的时候，从左往右依次运算；在计算小数乘加.乘减混合运算的时候，先算乘法，后算加减法；有括号的先算括号里面.2.小数的简便运算：小数乘法也可以运用整数乘法的交换律.结合律和分配律使一些计算简便. 乘法交换律：a×b = b×a乘法结合律：（a×b）×c=a×（b×c）乘法分配律：（a＋b）×c=a×c + b×c1.先说一说运算顺序，再计算.（1）2.8×5.3×1.3 （2）0.71+0.25×0.4 （3）5.5×1.52-2.032. 求近似值.（1）1.2×2.4 (保留一位小数) （2）0.11×0.53（精确到百分位）（1）0.25×4.78×4 （2）1.25×4×2.5×8（3）1.5×1014.计算下面各题，能用简便方法算的用简便方法算.（1）2.02×8.5 （2）1.25＋4.6＋0.75 （3）48×0.25（4）3.4×7×1.5 （5）2.33×0.5×0.4×5 （6）1.6×7.5×1.255.0.31×2.5 - 0.24先算（）A.加法B.减法C.乘法6. 3.6×4.5+3.6×5.5可以运用（）进行简算.A.乘法交换律B.乘法结合律C.乘法分配律1.玉山农场新建一座温室, 室内耕地面积是285平方米, 全部栽西红柿，平均每平方米产6千克.每千克按0.65元计算,一共可以收入多少元？。
北师大版 四年级下册 第9讲 小数的混合运算和简便运算(教师版)
教学辅导教案1.说一说下面各题的运算顺序分别是怎样的?⑴12×5×3 ⑵ 30×7＋85 ⑶250×4－320先算乘法再算加减法2.说一说用到什么运算定律，才能使下面的计算简便?⑴ 25×98×4 ⑵ 125×5×8×4 ⑶ 15×201（1）（2）乘法交换律（3）乘法分配律（拆分因数）知识点一：小数的混合运算1.按照混合运算的运算法则计算下列各式 .（1）2.6+1.4×1.5－1.5 （2）2.6+2.4×（1.4－1.05）=2.6+2.1-1.5 =2.6+2.4×0.35=4.7-1.5 =2.6+0.84=3.2 =3.44（3）(31.8+3.2×4) × 5 （4） 0.64×25×7.8+2.2=（31.8+12.8）×5 =16×7.8+2.2=44.6×5 =124.8+2.2=223 =127知识点二：运用交换律简便运算第1页共7页2 . 用简便方法计算（1）0.8 ×3.2×12.5 （2）19.4×4×2.5 （3）0.4×0.7×0.25 =0.8×12.5×3.2 =19.4×（4×2.5） =0.4×0.25×0.7=10×3.2 =19.4×10 =0.1×0.732 =194 =0.07知识点三：运用结合律简便运算（1）2.55×7.1+2.45×7.1 （2）1437×27＋27×563=7.1×（2.55+2.45） =27×（1437+563）=7.1×5 =27×200035.5 =54000（3）0.68×1.9+0.32×1.9 （4）52×99+52=1.9×（0.68+0.32） =52×99+52×1=1.9×1 =52×（99+1）=1.9 =52×100=5200知识点四：运用分配律简便运算（1）29×（10-0.1）（2） (0.123+123) ×100=29×10-29×0.1 =0.123×100+123×100=290-2.9 =12.3+12300=287.1 =12312.3（3） 31×99 (4) 25×10.1=33×（100-1） =25×（10+0.1）=33×100-33×1 =25×10+25×0.1=3300-33 =250+2.5=3267 =252.5知识点一：小数加减法的计算法则小数点对齐，并把相同的数位对齐，末位算起，哪一位上的数满十向前一位进一；哪1.4×8.7=12.18 5.2×6.3=32.763.7×2.5= 9.25 70×0.26=18.2知识点三：简便计算乘法分配率：（a+b）×c=a×c+b×c乘法交换律：a×b=b×a乘法结合律：a×（b×c）=（a×b）×c3.8×6.7+3.3×3.8 1.28×0.29-0.29×0.28 （4-0.4）×2.5=3.8×（6.7+3.3） =0.29×（1.28-0.28） =4×2.5-0.4×2.5 =3.8×10 =0.29×1 =10-138 =0.29 =9101×4.8 56×12.5 3.45×79+3.45 =（100+1）×4.8 =7×8×12.5 =3.45×（79+1）=100×4.8+1×4.8 =7×（8×12.5） =3.45×80=480+4.8 =7×100 =276=484.8 =7000.4×4.6×25 1.25×0.41×16 1.08×99+1.08=0.4×25×4.6 =1.25×0.41×8×2 =1.08×（99+1）=10×4.6 =1.25×8×0.41×0.2 =1.08×100=46 =10×0.41×0.2 =108=4.1×02.=0.821.计算.①（0.59+0.15）×0.12 ② 2.85 × 0.2 × 7.2 ③（8.6-1.7）×0.08=0.74×0.12 =0.57×7.2 =6.9×0.08=0.0888 =4.104 =0.5522.求近似值.①5.02 ×1.7（得数保留一位小数）②0.76 ×1.45 （结果精确到百分位）8.5 1.103.用简便方法计算.① 5.5×9.9 ②7.8 ×9+7.8 ③19.7× 5.3+ 4.7× 19.7 =5.5×（10-0.1） =7.8×（9+1） =19.7×（5.3+4.7）=55-0.55 =7.8×10 =19.7×10=54.45 =78 =1971.小数混合运算的顺序：在计算小数连乘的时候，从左往右依次运算；在计算小数乘加.乘减混合运算的时候，先算乘法，后算加减法；有括号的先算括号里面.2.小数的简便运算：小数乘法也可以运用整数乘法的交换律.结合律和分配律使一些计算简便.乘法交换律： a×b = b×a乘法结合律：（a×b）×c=a×（b×c）乘法分配律：（a＋b）×c=a×c + b×c1.先说一说运算顺序，再计算.（1）2.8×5.3×1.3 （2）0.71+0.25×0.4 （3）5.5×1.52-2.03 =14.84×1.3 =0.71+0.1 =8.36-2.03A.乘法交换律B.乘法结合律C.乘法分配律1.玉山农场新建一座温室, 室内耕地面积是285平方米 , 全部栽西红柿，平均每平方米产6千克.每千克按0.65元计算,一共可以收入多少元？285×6×0.65=1111.5（元）2.松柏林能分泌杀菌素，可以净化空气，如果1公顷松柏林每天分泌杀菌素54千克，24.5公顷松柏林31天分泌杀菌素多少千克？24.5×54×31=41013（千克）3.丽丽送给希望小学3名同学每人一套12.8元的文具和一本7.2元的《数学家的故事》,丽丽一共花了多少钱？3×（12.8+7.2）=60（元）4.一种花布的售价1米16.2元，请算出3.6米.12米.8.5米的花布的总价各是多少？3.6×16.2=58.32（元）12×16.2=194.4（元）8.5×16.2=137.7（元）。
北师大四年级数学下册小数乘法简便计算
四年级下册小数练习题一、脱式计算，能简算的要简算。
7.8×1.3+0.9 48-1.8×24 0.25×0.46×0.42.5×1.3+0.93.8×41-3.8 （4+0.4）×2.50.27×3.8+0.27×6.2 2.9×100.1 27.5×101-27.540×0.63×0.25 3.62×25.7+3.62×74.3 0.25×4.87×418.8+23.6+26.4 10.95-3.74-4.26 95.59-（9.59+12.78）25.6-(0.23+5.6)-1.77 13.75-(4.75+6.48) 7.83+2.34-0.83+6.66 3.82+2.9+0.18+9.1 5.93+0.19+2.81 25.48-((9.4-0.52)3.07-0.38-1.62 35.6-1.8-15.6-7.2 7.3+2.7-7.3+2.7 48.4+2.78+51.6-0.78 23.4+0.8-13.4-7.24.8+8.63+5.2+0.373.25+2.76+1.75 1.27+3.9+0.73+15.1 5.84-1.8-3.2 132.44-(58.74+19.44) 7.5+4.8-6.57.14-0.53-2.47 13.75-(3.75+6.48) 13.45-4.68+2.55 47.8-7.45+8.2 36.8-4.5+6.98 49.8-9.6+8.8 15.2-6.8-3.45 1.76+0.65+3.240.134+2.66+0.8 7.5+4.9-6.3 3.45+1.79+0.65 4.85+8.63+0.371.76+3.44+0.35 36.54-1.76-8.66 8-2.45-1.02 23.4+3.4-0.23 6.02+3.6+1.98 3.07-0.38-1.62 7.5+4.9-6.5 36.8-3.9-6.88 3.285+1.79+0.59 23.4-0.8+13.4 32+4.9-8.6 1.29+3.7+2.715.93+0.49+2.06 9-2.45-1.65 21+0.56+11.3 64.89-7.88-13.6二、能简便的要简便计算。
北师大版四年级下册小数简便运算
北师大版小学四年级下册小数的简便运算一、减法中的巧算1.减法的性质：a-b-c=a-（b+c）巧算下面各题：① 300-73-27 ② 7.42-(3.42+1.5) ③ 4723-（723＋189）二、加减混合式的巧算1.去括号和添括号的法则在只有加减运算的算式里，如果括号前面是“＋”号，则不论去掉括号或添上括号，括号里面的运算符号都不变；如果括号前面是“-”号，则不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“搬家”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。
3.找“基准数”法几个比较接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＋851.加法交换结合律：4.8＋0.25＋1.75= 57.8＋1.43＋2.2＋0.57= 1.28＋8.9＋0.72=16.7＋28.9＋3.3= 15.8＋39.5＋10.5= 8.22＋1.97＋0.78= 0.58＋0.39＋0.42＋0.61= 1.25＋0.75＋3.20 = 1.53＋0.38＋1.62=7.5＋3.4＋12.5＋36.6 = 1.63＋0.32＋1.37＋2.68=二、乘法中的巧算2.乘法交换结合律（一）：bcacba⨯⨯=⨯⨯（15×2.5）×4= 38×2.5×4= 35×2×0.5= （60×0.25）×4= 5×289×0.2= （1.25×5）×0.8= 2.5×17×0.4= 125×50×0.2=（2.5×12.5）×（8×4）= 38×12.5×0.8×3= 125×5×0.08×2=9×80×0.125= 2.5 ×12.5×32= 43×2.5×40=42×12.5×8= 60×0.25×40= 1.25×0.5×0.8= 2.5×17×0.4=3.乘法交换结合律（二）：）（）（b c a c b a ⨯⨯=⨯⨯12.5×32= 24×1.25= 0. 125×56= 1.25×72=12.5×1.6 = 4.8×125= 125 ×0.64= 2.5×3.6=4.乘法分配律（一）：)(c b a c a b a ±=⨯±⨯3.4×72＋3.4×28= 0.07×48＋0.07×52= 3.5×3.7＋6.5×3.7=0.85×8.2+8.2×0.15= 2.5×9.7+2.5×0.3= 76×0.25＋0.25×24 =5.乘法分配律（二）：添加因数“1”38×99＋38= 75× 299＋75= 102×99＋102=39＋9×39= 56.5×99＋56.5= 9.7×99＋9.7 = 4.2×99＋4.2= 5.4×11-5.4= 99×128 ＋128=6.乘法分配律（三）：cbcacba⨯±⨯=⨯±)(12.5×（8＋80 ）= 8×（125＋9）= （20＋4）×0.25=2.5×(4＋0.4)= （125＋40）×8= （12.5＋2.5）×8=7.乘法分配律（四）：一个因数都接近整数1、10、100等，这样的数就可以拆分成两个数相加或者相减。
北师大四年级数学下册小数乘法简便计算
四年级下册小数练习题一、脱式计算，能简算的要简算。
7.8×1.3+0.9 48-1.8×24 0.25×0.46×0.42.5×1.3+0.93.8×41-3.8 （4+0.4）×2.50.27×3.8+0.27×6.2 2.9×100.1 27.5×101-27.540×0.63×0.25 3.62×25.7+3.62×74.3 0.25×4.87×418.8+23.6+26.4 10.95-3.74-4.26 95.59-（9.59+12.78）25.6-(0.23+5.6)-1.77 13.75-(4.75+6.48) 7.83+2.34-0.83+6.66 3.82+2.9+0.18+9.1 5.93+0.19+2.81 25.48-((9.4-0.52) 3.07-0.38-1.62 35.6-1.8-15.6-7.2 7.3+2.7-7.3+2.7 48.4+2.78+51.6-0.78 23.4+0.8-13.4-7.2 4.8+8.63+5.2+0.37 3.25+2.76+1.75 1.27+3.9+0.73+15.1 5.84-1.8-3.2 132.44-(58.74+19.44) 7.5+4.8-6.57.14-0.53-2.47 13.75-(3.75+6.48) 13.45-4.68+2.55 47.8-7.45+8.2 36.8-4.5+6.98 49.8-9.6+8.8 15.2-6.8-3.45 1.76+0.65+3.240.134+2.66+0.8 7.5+4.9-6.3 3.45+1.79+0.65 4.85+8.63+0.371.76+3.44+0.35 36.54-1.76-8.66 8-2.45-1.02 23.4+3.4-0.23 6.02+3.6+1.98 3.07-0.38-1.62 7.5+4.9-6.5 36.8-3.9-6.88 3.285+1.79+0.59 23.4-0.8+13.4 32+4.9-8.6 1.29+3.7+2.715.93+0.49+2.06 9-2.45-1.65 21+0.56+11.3 64.89-7.88-13.6二、能简便的要简便计算。