考点:小数四则混合运算
专题:运算顺序及法则
分析:(1)运用乘法分配律简算;
(2)先把101分解成100+1,再运用乘法分配律简算;
(3)运用乘法分配律简算;
(4)先同时计算乘法和除法,再算减法;
(5)先同时计算两个小括号里面的减法,再算括号外的除法;
(6)先同时运算除法和乘法,再算减法;
(7)根据乘法交换律和结合律简算;
(8)先算小括号里面的减法,再算括号外的减法,最后算括号外的加法.
解答:
解:(1)4.2×7.8+2.2×4.2
=4.2×(7.8+2.2)
=4.2×10
=42;
(2)9.5×101
=9.5×(100+1)
=9.5×100+9.5×1
=950+9.5
=959.5;
(3)3.65×88+3.65×11+3.65
=3.65×(88+11+1)
=3.65×100
=365;
(4)49.5×0.2-2.07÷23
=9.9-0.09
=9.81;
(5)(1-0.2)÷(1-0.84)
=0.8÷0.16
=5;
(6)6.4÷0.8-1.5×4
=8-6
=2;
(7)2.6×1.9÷2.6×1.9
=(2.6÷2.6)×(1.9×1.9)
=1×3.61
=3.61;
(8)16.75-(9.1-1.92)+1.62
=16.75-7.18+1.62
=9.57+1.62
=11.19.
点评:此题是考查四则混合运算,要仔细观察算式的特点,灵活运用一些定律进行简便计算.