整数乘法的运算定律推广到小数.ppt

整数乘法的运算定律 推广到小数,乘法交换律,乘法结合律,ab=ba,(ab)c=a(bc),乘法分配律,(ab)c=acbc,a(bc)=abac,=,(2.43.6)0.5 2.40.53.60.5,=,=,乘法交换律,乘法结合律,乘法分配律,整数乘法的交换律、结合律和分配律，对于小数乘法也适用。,0.253.574 3.57（_）2.630.5 4 _（_ _）0.75(200+1)_ _6.70.70.36.7_（_）,0.25 4,2.63 0.5 4,0.75 200 0.75,6.7 0.7 0.3,0.0340.50.6,1020.45,0.034（0.50.6）,0.0340.3,0.0102,（1002）0.45,1000.4520.45,45 0.9,45.9,乘法结合律,乘法分配律,2.50.734,0.73（2.54）,0.7310 7.3,（1.252.5）8,1.2582.58,1020 30,乘法交换律,乘法结合律,乘法分配律,7.2997.2,7.2（991）,7.2100 720,0.2512,0.25（43）,0.2543 13,7.2997.21,3,乘法结合律,乘法分配律,0.125320.25,（0.1258）（0.254）,11 1,0.125（84）0.25,乘法交换律,乘法结合律,986.5（982）6.5 100 6.5 650,12.52.53.2 12.52.5（80.4）12.582.50.4 1001 101,这样算对吗？如果不对，错在那里？,乘法分配律,乘法交换律,乘法结合律,