第二讲 小数的简便运算(二) 例题讲解: [例题1](1+0.28+0.84)×(0.28+0.84+0.66)-(1+0.28+0.84+0.66)×(0.28+0.84) 分析:设a=1+0.28+0.84 b=0.28+0.84,那么a-b=1 原式=a×(b+0.66)-(a+0.66)×b =a×b+a×0.66-a×b-0.66×b =0.66×(a-b) =0.66×1 0.66 [例题2]a=0.000...025,b=0.000...016 计算a+b,a-b,a×b,a÷b 1994个0 1995个0 解: 0.000...025 0.000...025 + 0.000...0016 -0.000...0016 0.000...0266 0.000...0234 1994个0 1994个0 a×b=0.000...0400=0.000...04 1996+1997位 3990个0 a÷b=0.000...025÷0.000...016=250÷16=15.625 1994个0 1995个0 [例题3]1÷0.1÷0.01÷0.001÷0.0001÷...0.00...01 10个0 分析:一个数除以0.1,0.01,0.001...也就是把这个数扩大10倍,100倍,1000倍...化除为乘,使计算简便.