1、小数乘法的简便运算 五年级五年级比较一下比较一下,哪边的计算更简便哪边的计算更简便.(3.22.8) 0.6 3.20.62.80.61.25230.8 1.250.823小数小数 整数整数下面计算运用了什么定律下面计算运用了什么定律.(1.25+2.5) 0.8 = 1.250.8+2.50.82.53.24 = 3.2(2.54)填空填空:0.258.94 = 0.25( )( )3.22.8-3.20.8 = 3.2( - )9.21.01 = 9.2( ) + 9.2( )4.10.99 = 4.1( ) - 4.1( )12.50.438 2.51.25325.61.35.68.7
2、2.5(400.4)3.2993.2 3.21.017.210.27.20.2 7.2(100.1)7.21017.2 0.6199口算口算:1.2580= 50.6=0.60.08= 1.25=200.05= 4.32=3.510= 0.213=口算口算:1.2580= 100 50.6= 30.60.08= 0.048 1.25= 6200.05= 1 4.32= 8.63.510= 0.35 0.213= 0.07 7.11.01 7.1 0.430.99 0.99 3.50.63 3.5比一比比一比,谁算得又对又快谁算得又对又快: 4.05233.20.7562.4610.886411.546 2.50.99=2.51000.01=2500.01=249.99 2.50.99=2.512.50.01 2.520.1=2.5202.51=502.5=52.5 2.520.1=2.5202.50.1 1.25 2.532=1.2582.54=1010=20 1.25 2.532=(1.258)(2.54) 2.54.8=2.552.50.2=12.50.5=12 2.54.8=2.541.2
